Bundle releases include pre-release library releases

[EGJ-Moorington]

The automatic bundle releases made by @adafruit-adabot include releases of libraries marked as pre-release. I suggest releases of the bundle marked as stable should only include stable library releases.

Library pre-release releases could either be ignored entirely or @adafruit-adabot could make pre-release releases of the bundle which include pre-releases of libraries.

If @adafruit-adabot can't differentiate pre-release from stable releases via GitHub's Releases, it could treat any tags on non-default branches as pre-releases.