fix(prepare-release): commit all files

As the release is now prepared on a neutral machine there is no way that there are dirty files lying around.

* * *

This commit was sponsored by The Hoodie Firm.
You can hire The Hoodie Firm:
http://go.hood.ie/thehoodiefirm
feat(prepare-release): programatically detect bump files

This removes the need to configure this task entirely (in 99% of the cases).

* * *

This commit was sponsored by The Hoodie Firm.
You can hire The Hoodie Firm:
http://go.hood.ie/thehoodiefirm
chore(grunt): it's magic :sparkles:

* * *

This commit was sponsored by The Hoodie Firm.
You can hire The Hoodie Firm:
http://go.hood.ie/thehoodiefirm