Bump the mailman-hyperkitty plugin to 1.2.0.
Bump the mailman-hyperkitty plugin to 1.2.0.

This new version sends the api_key as an Authorization header instead of
a GET parameter, which fixes a security vulnerability. The change is needed
since Hyperkitty has been upgraded to 1.3.5.

maxking/docker-mailman,maxking/docker-mailman