Release Metafacture core 5.5.0

[dr0i]

Follows up #470.

Next release following metafacture-core-5.4.0. Current HEAD at 8a3e605.

• test release candidate
• release on maven central
• release on github
• update flux-commands
• write blog post, see PR
• toot
• write to email list

Enables metafacture/metafacture-fix#286.

[blackwinter]

👍 Ran both Metafix and Limetrans tests with 5.5.0 RC1. ✔️

[dr0i]

Released metafacture-core-5.5.0-rc1-SNAPSHOT to sonatype. See https://github.com/metafacture/metafacture-core/wiki/Maintainer-Guidelines#consume-the-snapshot how to consume it.

[dr0i]

Ran with lobid-resources. ✔️

[fsteeg]

Tested metafacture-core-5.5.0-rc1-SNAPSHOT via Sonatype with rpb, oersi, and playground ✔️

[dr0i]

Github release ready, please have a look at the description https://github.com/metafacture/metafacture-core/releases/tag/metafacture-core-5.5.0 if anything is missing etc. This will be the base for the blog post.

[blackwinter]

👍 (Minor nitpicks: Why io instead of IO? Why mixed lower and upper case after colon?)