add workflow for release automation

[AlvinSchiller]

Added a workflow to automatically create releases on merging to master.

Implemented Process

• Every push to master triggers the action to create a release
• The action
  • checks if it should run
    • only on the MainRepo "MiczFlor"
    • only for branches master
    • on master only if the version in ./settings/version-number is a release version*
  • if no release for the version is found, one is created (type release with generated releasenotes) incl. tag
  • updates the release, but name and body will not be overwritten.

* version string are validated against Semantic Versioning format
e.g. release: 1.0.0, 3.5.0, 100.4.50000+metadata
e.g. prerelease: 1.0.0-alpha, 3.5.0-whatsoever.12, 100.4.50000-identifier.12+metadata

Prior to merging to master the version in ./settings/version-number has to be updated to the next release version.
If the version merged to master is still a prerelease version, the workflow is aborted.

Demo

• Test Branch with current changes (demo versionnumber 2.5.0-alpha)
• Pull Request to merge changes. Action is not triggerd.
• Merge on AlvinSchiller/develop results in Action is not triggerd.
• New Commit on AlvinSchiller/develop results in Action is not triggerd.
• Pull Request to merge changes to AlvinSchiller/master. Action is not triggerd (don't know why the last run from the commit is shown in checks)
• Merge on AlvinSchiller/master results in Action run but cancels due to incorrect release version number
• New Commit on AlvinSchiller/develop to change version number to release results in Action is not triggerd.
• Pull Request to merge changes to AlvinSchiller/master. Action is not triggerd (don't know why the last run from the commit is shown in checks)
• Merge on AlvinSchiller/master results in Action run and creation of Tag and Release v2.5.0 including releasenotes and latest flag
• New Commit on AlvinSchiller/master results in Action run andupdates existing Release v2.5.0
• New Commit on AlvinSchiller/master to change version number to next bugfix release results in Action run and creation of Tag and Release v2.5.1 including releasenotes

[coveralls]

Pull Request Test Coverage Report for Build 7269270135

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 76.82%

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Totals
Change from base Build 7182031367:	0.0%
Covered Lines:	633
Relevant Lines:	824

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💛 - Coveralls