Add Dependabot

[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?:

• Adds a dependabot configuration for updating pip and GitHub Action dependencies

Does this PR introduce a breaking change?:

Nope.

Other information:

https://docs.github.com/en/code-security/dependabot/working-with-dependabot

[coveralls]

Pull Request Test Coverage Report for Build 7846166831

• 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 72.656%

---

Totals
Change from base Build 7846163165:	0.0%
Covered Lines:	1767
Relevant Lines:	2432

---

💛 - Coveralls