こんにちは。
表題の件です。

ActiveRecord::PendingMigrationError
Migrations are pending. To resolve this issue, run: bin/rake db:migrate RAILS_ENV=development

上記のエラーが表示されます。
なぜでしょうか？

ユーザーのログイン機能を実装しようとしました。
このまえに行ったこと。

◆ターミナル
rails g devise User
rake db:migrate

◆user.rb
class User < ActiveRecord::Base

Include default devise modules. Others available are:

:confirmable, :lockable, :timeoutable and :omniauthable

devise :database_authenticatable, :registerable,
:validatable
has_many :notes

validates :name, presence: true

validates :email, presence: true, uniqueness: true

validates :name, presence: true

validates :email, presence: true, uniqueness: true

def set_image(file)
if !file.nil?
file_name = file.original_filename
File.open("public/user_images/#{file_name}", 'wb'){|f| f.write(file.read)}
self.image = file_name
end
end

end

◆add_devise_to_users.rb

class AddDeviseToUsers < ActiveRecord::Migration
def self.up
change_table(:users) do |t|
## Database authenticatable
# t.string :email, null: false, default: ""
t.string :encrypted_password, null: false, default: ""

  ## Recoverable
  # t.string   :reset_password_token
  # t.datetime :reset_password_sent_at

  ## Rememberable
  # t.datetime :remember_created_at

  ## Trackable
  # t.integer  :sign_in_count, default: 0, null: false
  # t.datetime :current_sign_in_at
  # t.datetime :last_sign_in_at
  # t.string   :current_sign_in_ip
  # t.string   :last_sign_in_ip

  ## Confirmable
  # t.string   :confirmation_token
  # t.datetime :confirmed_at
  # t.datetime :confirmation_sent_at
  # t.string   :unconfirmed_email # Only if using reconfirmable

  ## Lockable
  # t.integer  :failed_attempts, default: 0, null: false # Only if lock strategy is :failed_attempts
  # t.string   :unlock_token # Only if unlock strategy is :email or :both
  # t.datetime :locked_at


  # Uncomment below if timestamps were not included in your original model.
  # t.timestamps null: false
end

# add_index :users, :email,                unique: true
# add_index :users, :reset_password_token, unique: true
# add_index :users, :confirmation_token,   unique: true
# add_index :users, :unlock_token,         unique: true

end

def self.down
# By default, we don't want to make any assumption about how to roll back a migration when your
# model already existed. Please edit below which fields you would like to remove in this migration.
raise ActiveRecord::IrreversibleMigration
end
end

ご回答お願いします！！！