ci : add release job and include xcframework (#2889)

ci : add release job and include xcframework (#2889)

* ci : add release job and include xcframework

This commit adds a release job that uploads the xcframework as an
artifact and creates a release with the xcframework as an asset.

This job can be triggered manually and enables a pre-release tag name to
be specified to that these releases can be distinguished from the
regular releases more easily.

Resolves: https://github.com/ggerganov/whisper.cpp/issues/2886