Hi there,

I noticed that the mySQL Support seems to be dropped since version 8.3.

To verify I'm using the following docker-compose to test out new versions:

version: '3'
services:
  openproject:
    # Default login ist: admin/admin
    # 8.2.1 works with mysql / >=8.3 is broken due to missing mysql Adaptor
    # image: openproject/community:8.3.2
    image: openproject/community:8.2.1
    
    # NOTICE: NOT SUPPORTED YET! CONTAINTER IS INSECURE
    # do not run as privileged user! (Security-Constraint)
    # user: app
    
    environment:
      - SECRET_KEY_BASE=secret
    # data can be stored locally onto the file system or within an SQL DB
      - DATABASE_URL=mysql2://opapp:opapp@db:3306/projectdb
    # for filesystem create something like /var/lib/openproject on your host and mount it into the container
    # volumes:
    #
    #  - /var/lib/openproject/pgdata:/var/openproject/pgdata
    #  - /var/lib/openproject/static:/var/openproject/assets
    #
    # TO Simulate SMTP Connectivity we are using a fake-mailer (WebGUI is listening on http 5080 / admingui on 5081)
      - EMAIL_DELIVERY_METHOD=smtp
      - SMTP_ADDRESS=fakemailer
      - SMTP_PORT=5025
      - SMTP_DOMAIN=wdr.de
      - SMTP_AUTHENTICATION=login
      - SMTP_ENABLE_STARTTLS_AUTO=true
      - SMTP_USER_NAME=SomeAPIUser
      - SMTP_PASSWORD=SomeAPIUserPasswd
     # Temp Path Folder to keep container from growing
     # - OPENPROJECT_STORAGE_TMP__PATH=/var/openproject/tmp
    ports:
      # WebGUI
      - 8080:80
      # Email-Verification REST endpoint? (needs to be verified - or should 8080 better 3000 for this workflow?)
      - 3000:3000
    depends_on:
      - db
  db:
    image: mariadb:10.2
    environment:
      - MYSQL_ROOT_PASSWORD=SuperDooper
      - MYSQL_DATABASE=projectdb
      - MYSQL_USER=opapp
      - MYSQL_PASSWORD=opapp
    command: --character-set-server=utf8mb4 --collation-server=utf8mb4_unicode_ci
    ports:
      - 3306:3306
  fakemailer:
    # see https://github.com/gessnerfl/fake-smtp-server
    image: gessnerfl/fake-smtp-server:1.2.0
    environment:
      - fakesmtp.authentication.username=SomeAPIUser
      - fakesmtp.authentication.password=SomeAPIUserPasswd
    ports:
      - 5025:5025
      - 5080:5080
      - 5081:5081