Update Github Action for Gradle

[unp1]

Intended Change

Parts of the currently used configuration syntax will soon be depracted. This PR updates them to the new syntax

Type of pull request

• There are changes to the deployment/CI infrastructure (gradle, github, ...)

Ensuring quality

• I have tested the feature as follows:
  • [x] The github actions in this PR work as intended

Additional information and contact(s)

The contributions within this pull request are licensed under GPLv2 (only) for inclusion in KeY.

[wadoon]

Pointer to the deprecation warning:

https://github.com/gradle/actions/blob/main/docs/deprecation-upgrade-guide.md#using-the-action-to-execute-gradle-via-the-arguments-parameter-is-deprecated