Add helper script for preparing and publishing releases
This is a somewhat over-engineered script to help with preparing and publishing freedesktop-sdk releases.
I need to properly document this before this is merged (likely here). Basic usage is:
$ ./utils/release.py prepare release/21.08 freedesktop-sdk-21.08.20
$ ./utils/release.py publish $GL_TOKEN freedesktop-sdk-21.08.20 51a8ec0bbc67e019358a9a26e4691d29c1998b4e