Bump calendar-js from `1c4fbb9` to `c1bf1a2`

Bumps [calendar-js](https://github.com/georgehrke/calendar-js) from `1c4fbb9` to `c1bf1a2`.
- [Release notes](https://github.com/georgehrke/calendar-js/releases)
- [Commits](https://github.com/georgehrke/calendar-js/compare/1c4fbb97e1d34981b658f8d2171bd488282cb62e...c1bf1a23b0422416390c58aede640f280cdc1c78

)

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