Is your feature request related to a problem? Please describe.
We try to enforce signed commits on our projects to ensure people are who they say they are when they commit to a repo, but we have to turn this setting off when creating repo's that can be committed to by Netlify cms.

Describe the solution you'd like
A way to have signed commits, possibly verified by using gpg keys.

Describe alternatives you've considered
Making a specific github account/repo seperate for the cms commits.

Additional context
There may be a way to do this currently that I can't think of or find an idea on how to start going about it.