Enable Branch Protection for master and release/** branches

[mlachenmayr-celonis]

To align with OpenSSF (Open Source Security Foundation) best practices and improve the project's Scorecard rating, I recommend enabling GitHub Branch Protection rules for the master branch and all release/** patterns.

This check determines whether a project's default and release branches are protected with GitHub's branch protection or repository rules settings. Branch protection allows maintainers to define rules that enforce certain workflows for branches, such as requiring review or passing certain status checks before acceptance into a main branch, or preventing rewriting of public history.

Full documentation can be found here: https://github.com/ossf/scorecard/blob/80ee3ecfedf8b19ab8991713a9fdb2e7dcd7262e/docs/checks.md#branch-protection

Since this needs to be done in the settings with admin privileges I cannot provide a PR to assist you with that.