update npm dependencies

It seems like we have missed a few releases.

Relevant changelogs:

-   https://blog.getbootstrap.com/2021/01/19/bootstrap-4.6.0/
-   https://github.com/fullcalendar/fullcalendar/blob/master/CHANGELOG.md
    -   icalendar support could be interesting
-   https://github.com/dmester/jdenticon/releases
-   https://eslint.org/blog/2020/02/whats-coming-in-eslint-7.0.0