Bump github.com/arran4/golang-ical from 0.2.1 to 0.2.8

Bumps [github.com/arran4/golang-ical](https://github.com/arran4/golang-ical) from 0.2.1 to 0.2.8.
- [Release notes](https://github.com/arran4/golang-ical/releases)
- [Commits](https://github.com/arran4/golang-ical/compare/v0.2.1...v0.2.8

)

---
updated-dependencies:
- dependency-name: github.com/arran4/golang-ical
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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