Bump icalendar from 2.11.2 to 2.12.0

Bumps [icalendar](https://github.com/icalendar/icalendar) from 2.11.2 to 2.12.0.
- [Changelog](https://github.com/icalendar/icalendar/blob/main/CHANGELOG.md)
- [Commits](https://github.com/icalendar/icalendar/compare/v2.11.2...v2.12.0)

---
updated-dependencies:
- dependency-name: icalendar
  dependency-version: 2.12.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Gemfile.lock

@@ -337,7 +337,7 @@ GEM
       terminal-table (>= 1.5.1)
     i18n_data (1.1.0)
       simple_po_parser (~> 1.1)
-    icalendar (2.11.2)
+    icalendar (2.12.0)
       base64
       ice_cube (~> 0.16)
       logger