pdo_sqlsrvがssl関連のエラーを出す

docker-composeでnginxとphp-fpmにpdo_sqlsrvを入れたのを使ってsqlserverと通信したいです。
phpinfo()ではpdo_sqlsrvとsqlsrvが入っているのが確認できるのですが、実行すると以下のようなエラーが出ます

SQLSTATE[08001]: [Microsoft][ODBC Driver 18 for SQL Server]SSL Provider: [error:1416F086:SSL routines:tls_process_server_certificate:certificate verify failed:self signed certificate]

構成をapacheからnginx＋php-fpmに乗り換えたのですが、
apacheの時には普通に接続できていました

ファイル

test.php

php
1<?php
2
3$db_address = '***.***.***.***';
4$db_name = 'testdb';
5$db_user = 'testuser';
6$db_pass = 'pass123@';
7try{
8   $db  = new PDO("sqlsrv:server=$db_address;database=$db_name",$db_user, $db_pass);
9}catch(PDOException $e){
10    echo $e->getMessage();
11}

docker-compose.yml
＊参考にしたサイト
＊alpineやバージョン指定はしていません

version: '3'

volumes:
  php_sockert:

services:
  nginx:
    container_name: test_nginx
    image: nginx:stable
    ports:
      - 28000:80
    volumes:
      - ./html/:/var/www/html/
      - ./nginx/nginx.conf:/etc/nginx/nginx.conf
      - ./nginx/default.conf:/etc/nginx/conf.d/default.conf
      - php_sockert:/var/run

  php_fpm:
    container_name: test_php_fpm
    build: ./php/
    volumes:
      - ./html/:/var/www/html
      - ./php/zzz-www.conf:/usr/local/etc/php-fpm.d/zz.conf
      - php_sockert:/var/run

php-fpmのDockerfile
＊参考にしたサイト様のコメント（#）は残しています
＊2020年版だったのでいくつか変更しています

# Install basic packages and extensions
RUN apt update
RUN apt install -y zlib1g-dev libzip-dev wget gnupg vim tree
RUN docker-php-ext-install zip opcache

# # Install SQL Server extensions
RUN curl https://packages.microsoft.com/keys/microsoft.asc | apt-key add -
# RUN curl https://packages.microsoft.com/config/debian/10/prod.list > /etc/apt/sources.list.d/mssql-release.list
RUN curl https://packages.microsoft.com/config/debian/11/prod.list > /etc/apt/sources.list.d/mssql-release.list
RUN apt update
RUN ACCEPT_EULA=Y apt install -y msodbcsql18 mssql-tools18
RUN echo 'export PATH="$PATH:/opt/mssql-tools18/bin"' >> ~/.bashrc
RUN . ~/.bashrc
RUN apt install -y unixodbc-dev libgssapi-krb5-2
RUN pecl install sqlsrv
RUN pecl install pdo_sqlsrv
RUN docker-php-ext-enable sqlsrv
RUN docker-php-ext-enable pdo_sqlsrv

default.conf

server {
    listen  80;
    server_name  localhost;
    root    /var/www/html;

    location    / {
        root    /var/www/html;
    }

    error_page   500 502 503 504  /50x.html;
    
    location = /50x.html {
        root   /usr/share/nginx/html;
    }

    location ~ \.php$ {
        root           /var/www/html/;
        fastcgi_pass   unix:/var/run/php7-fpm.sock;
        fastcgi_index  index.php;
        fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;
        include        fastcgi_params;
    }
}

nginx.conf

user  www-data;
worker_processes  1;

error_log  /var/log/nginx/error.log warn;
pid        /var/run/nginx.pid;


events {
    worker_connections  1024;
}


http {
    include       /etc/nginx/mime.types;
    default_type  application/octet-stream;

    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"';

    access_log  /var/log/nginx/access.log  main;

    sendfile        on;
    autoindex       on;
    #tcp_nopush     on;

    keepalive_timeout  65;

    #gzip  on;

    include /etc/nginx/conf.d/*.conf;
}