Bump icalendar from 5.0.12 to 6.1.0

Bumps [icalendar](https://github.com/collective/icalendar) from 5.0.12 to 6.1.0.
- [Release notes](https://github.com/collective/icalendar/releases)
- [Changelog](https://github.com/collective/icalendar/blob/main/CHANGES.rst)
- [Commits](collective/icalendar@v5.0.12...v6.1.0)

---
updated-dependencies:
- dependency-name: icalendar
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

requirements.txt

@@ -33,7 +33,7 @@ olefile==0.47
 Pillow==10.1.0
 vobject==0.9.6.1
 msglite==0.30.0
-icalendar==5.0.12
+icalendar==6.1.0
 
 cryptography==41.0.7
 requests[security]==2.31.0