Improve build configuration

[rsteph-de]

• Fix the following warning on Github Actions:

Node.js 20 actions are deprecated. The following actions are running on Node.js 20 and may not work as expected: actions/checkout@v4, actions/setup-java@v4.

• disable gpg signing from deploy-to-sonatype profile (not required for SNAPSHOT-Builds)

  • if you want to deploy a release enable the gpg-signing via maven profile:
    $ mvn release:perform -Psign-with-gpg -Pdeploy-to-sonatype

• increase version of Sonatype release plugin