Base versionCode at release builds on something independend from Github run numbers

see: https://github.com/msasikanth/twine/issues/1305#issuecomment-4181325902 **TL;DR:** GH run numbers are not accessible from outside their workflow, so independent builds (like our [Reproducible Builds](https://izzyondroid.org/about/security/ReproducibleBuilds/)) are unable to produce an identical APK without manual adjustments on each run. Further, please consider to disable [Native Library Stripping](https://izzyondroid.org/docs/reproducibleBuilds/DebugFailedRBs/#native-library-stripping), which require the matching NDK to be present at those RBs (which are otherwise not needed).