enable github's dependabot for dev env
https://github.com/fphammerle/ical2vdir/commit/76bc605ceba2ba3db9001a43a752da1ff9b9491f
https://github.com/fphammerle/ical2vdir/commit/8ec47f9dcbd9a10da5a7f8ab8fdaddf855d4dec6
https://github.com/fphammerle/python-manchester-code/commit/88d7d6636f906293ac1a22fd31f42a144d28c6aa