Modernisations and prepare v0.13.1

[Zeitsperre]

Pull Request Checklist:

• [ ] This PR addresses an already opened issue (for bug fixes / features)
  • This PR fixes issue #xyz
• [ ] Tests for the changes have been added (for bug fixes / features)
• [ ] Documentation has been added / updated (for bug fixes / features)
• [x] HISTORY.rst has been updated (with summary of main changes)
• [x] I have added my relevant user information to AUTHORS.md

What kind of change does this PR introduce?:

• Prepares the next patch release
• Places some lower boundary pins on existing dependencies
• Sets the GitHub Actions to use version hashes

Does this PR introduce a breaking change?:

No.

[coveralls]

Pull Request Test Coverage Report for Build 10460345696

Details

• 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 72.547%

---

Totals
Change from base Build 10459074296:	0.0%
Covered Lines:	1789
Relevant Lines:	2466

---

💛 - Coveralls