All packages whose name starts with `gi` are ignored

[maciej-gol]

After the change introduced here https://github.com/spulec/freezegun/issues/321, any package whose name starts with gi does not get their time frozen.

This happens both for 3rd party packages (like gitlab) and for local packages (like gitlab_my_helper).

I was looking into ways how to fix it, and came up with two solutions:

• allow ignore list to be regexes, and rewrite the default ignore list to regexes
• change the gi ignore entry to gi.