Gitpod support is broken after latest changes for codespaces.

[ESJBRE1]

It is neccesary to restore previous Dockerfile to add support for Gitpod.

• https://github.com/spring-projects/spring-petclinic/blob/main/.gitpod.yml
• https://github.com/spring-projects/spring-petclinic/commit/12eb8b1ff3b463fa3cf430fd202449f41397291d#diff-13bd9d7a30bf46656bc81f1ad5b908a627f9247be3f7d76df862b0578b534fc6

[dsyer]

See 42e2c74