Bump mysql to 8.0.29 to provide full development compatibility on arm64

This commit updates the the mysql docker image tag to 8.0.29.

Updating mysql to 8.0.29 and its corresponding docker tag (`mysql:8.0.29`) improves the support for developing and running on arm64 architectures and Apple Silicon machines.

Related: gematik#9

## Explanation:
 
Currently, the used docker image for mysql (`mysql:8.0.22`) is published only for architecture `linux/amd64` and has be used with Apple's Rosetta compatibility layer enabled.

`mysql:8.0.29` is the first **stable** version also targeting arm64.

### References:

- Docker Hub entry for 8.0.22: https://hub.docker.com/layers/library/mysql/8.0.22/images/sha256-7d83f4d89c92d7e72b366cc9d0f5c19b12cba934c5e135d21d81b2b84651df69?context=explore
- Docker Hub entry for 8.0.29: https://hub.docker.com/layers/library/mysql/8.0.29/images/sha256-12cf01a51f803d0ad49ee0dbbb3025a6eef3341e24757c2ed8150b6654c3fb07?context=explore

### Disclaimer:

A quick review of mysql's version changelog shows no compatibility issues.
All unit tests finished without any issues.

### Workaround:

Add the `platform` property to the docker service to trigger Rosetta 2 on Apple Silicon:

```yaml
services:
  # Database
  db:
    image: mysql:8.0.29
    container_name: idp-mysql
    <<: [*service-network-ref, *service-setup-ref]
    environment:
      MYSQL_ROOT_USER: root
      MYSQL_ROOT_PASSWORD: idp
      MYSQL_DATABASE: IDP
      <<: *environment-timezone-ref
    ports:
      - "8572:3306"
    volumes:
      - idp-data-db:/var/lib/mysql
    healthcheck:
      test: "/usr/bin/mysql --user=root --password=idp --execute \"SHOW DATABASES;\""
      interval: 20s
      timeout: 20s
      retries: 10
    # in case of development on Apple Silicon to trigger Rosetta 2
    platform: linux/amd64
```

docker-compose-ref.yml

@@ -25,7 +25,7 @@ x-service-network: &service-network-ref
 services:
   # Database
   db:
-    image: mysql:8.0.22
+    image: mysql:8.0.29
     container_name: idp-mysql
     <<: [*service-network-ref, *service-setup-ref]
     environment: