Release Metafacture core 6.1.1

[dr0i]

This release fixes bugs introduced in 6.1.0 (#527 (comment)).

• update dependencies if these are promising to not break much (540 update dependencies #541)
• test release candidates
• release on maven central
• release on github
• release metafacture-fix 1.1.1
• release metafacture-playground 1.1.1
• update flux-commands
• copy metafacture-fix' functions-and-cookbook to metafacture-documentation/Fix-function-and-Cookbook.md
• write blog post, see PR
• toot
• write to email list
• announce at [metadaten.community](https://metadaten.community/t/neue-metafacture-releases-core-6-1-1-fix-1-1-1-playground-1-1-1/...

[dr0i]

Based on the master and #541 the sonatype SNAPSHOT release 6.1.1-rc1-SNAPSHOT and github packages 6.1.1-rc1-SNAPSHOT are ready . See wiki/Maintainer-Guideline how to use it. Please test it and check mark:

• lobid-resources (@dr0i)
• playground (@dr0i, @TobiasNx )
• limetrans (@blackwinter)
• fix (@fsteeg)

[dr0i]

@TobiasNx I ve deployed test.metafacture.org/playground which shows the fixes bug you reported are fixed, please check.

[dr0i]

Closed in favor of #551.