SpringBoot + Spring JPA + PostgreSQLでEC2インスタンスよりAmazon RDSのデータを取得したい

前提・実現したいこと

SpringBoot + Spring JPA + PostgreSQLでAmazon RDSに格納したデータを出し入れするWebAPIを作成しています。

ローカル環境では正常起動しRDSへの接続も確認できているのですが、
パッケージを実行可能なJARとしてエクスポート（必須ライブラリをサブフォルダーにコピー）し、EC2上のLinux2環境に乗せてjavaコマンドで実行した際に下記エラーが発生しました。

似たような質問を読み漁り、解決を試みたものの、根本原因及び解決方法が見つからないので質問させていただきます。

発生している問題・エラーメッセージ

 /\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ / _` | \ \ \ \
 \/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::                (v2.4.2)

2021-02-16 11:11:02.872  INFO 62498 --- [           main] com.example.demo.DemoApplication         : Starting DemoApplication using Java 11.0.10 on ip-xxx-xx-xx-xx.ap-northeast-1.compute.internal with PID 62498 (/home/ec2-user/sample.jar started by root in /home/ec2-user)
2021-02-16 11:11:02.875  INFO 62498 --- [           main] com.example.demo.DemoApplication         : No active profile set, falling back to default profiles: default
2021-02-16 11:11:04.003  INFO 62498 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Bootstrapping Spring Data JPA repositories in DEFAULT mode.
2021-02-16 11:11:04.113  INFO 62498 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Finished Spring Data repository scanning in 83 ms. Found 4 JPA repository interfaces.
2021-02-16 11:11:05.834  INFO 62498 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2021-02-16 11:11:05.856  INFO 62498 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2021-02-16 11:11:05.857  INFO 62498 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.41]
2021-02-16 11:11:05.977  INFO 62498 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2021-02-16 11:11:05.977  INFO 62498 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 3022 ms
2021-02-16 11:11:06.549  WARN 62498 --- [           main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaConfiguration': Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in class path resource [org/springframework/boot/autoconfigure/jdbc/DataSourceConfiguration$Hikari.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.zaxxer.hikari.HikariDataSource]: Factory method 'dataSource' threw exception; nested exception is org.springframework.boot.autoconfigure.jdbc.DataSourceProperties$DataSourceBeanCreationException: Failed to determine a suitable driver class
2021-02-16 11:11:06.552  INFO 62498 --- [           main] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]
2021-02-16 11:11:06.602  INFO 62498 --- [           main] ConditionEvaluationReportLoggingListener :

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2021-02-16 11:11:06.641 ERROR 62498 --- [           main] o.s.b.d.LoggingFailureAnalysisReporter   :

***************************
APPLICATION FAILED TO START
***************************

Description:

Failed to configure a DataSource: 'url' attribute is not specified and no embedded datasource could be configured.

Reason: Failed to determine a suitable driver class


Action:

Consider the following:
        If you want an embedded database (H2, HSQL or Derby), please put it on the classpath.
        If you have database settings to be loaded from a particular profile you may need to activate it (no profiles are currently active).

apprication.properties

spring.jpa.database=POSTGRESQL
spring.datasource.driver-class-name=org.postgresql.Driver
spring.datasource.url=jdbc:postgresql://database-x.xxxxx.ap-northeast-1.rds.amazonaws.com:5432/testdb
spring.datasource.username=username
spring.datasource.password=password

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.4.2</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.example</groupId>
	<artifactId>demo</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>demo</name>
	<description>Demo project for Spring Boot</description>
	<properties>
		<java.version>11</java.version>
	</properties>
	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-jpa</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-jdbc</artifactId>
		</dependency>
		<dependency>
			<groupId>org.postgresql</groupId>
			<artifactId>postgresql</artifactId>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>

</project>