Bump icalendar from 6.1.0 to 6.1.1

Bumps [icalendar](https://github.com/collective/icalendar) from 6.1.0 to 6.1.1.
- [Release notes](https://github.com/collective/icalendar/releases)
- [Changelog](https://github.com/collective/icalendar/blob/main/CHANGES.rst)
- [Commits](collective/icalendar@v6.1.0...v6.1.1)

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

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements.txt

@@ -106,7 +106,7 @@ gitpython==3.1.44
     # via prospector
 gunicorn==23.0.0
     # via -r requirements.in
-icalendar==6.1.0
+icalendar==6.1.1
     # via
     #   -r requirements.in
     #   django-ical