This adds a Danger check to produce a warning for MR titles greater than
72 characters. This is necessary because when squash on merge is used,
the MR title will be used for the commit message (at least by default).
This in turn leads to commit messages that violate our commit message
guidelines.

For more information, refer to
https://gitlab.com/gitlab-org/release/framework/issues/24.

If it's most of the time, then it's not all.

Signed-off-by: Rémy Coutable <remy@rymai.me>

Signed-off-by: Rémy Coutable <remy@rymai.me>