Update icalendar requirement from ~=6.1.1 to ~=6.1.2

Updates the requirements on [icalendar](https://github.com/collective/icalendar) to permit the latest version.
- [Release notes](https://github.com/collective/icalendar/releases)
- [Changelog](https://github.com/collective/icalendar/blob/main/CHANGES.rst)
- [Commits](collective/icalendar@v6.1.1...v6.1.2)

---
updated-dependencies:
- dependency-name: icalendar
  dependency-type: direct:production
...

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

Author: dependabot[bot]

requirements.txt

@@ -8,4 +8,4 @@ requests~=2.32.3
 python-dotenv==1.0.1
 colorama~=0.4.6
 django-q2==1.7.6
-icalendar~=6.1.1
+icalendar~=6.1.2