Allow a prefix string before "feat:"

[elliot-nelson]

I like to use gitmoji on personal projects, so ideally if my commit message is ":sparkles: feat: something" or ":bento: feat: something" it would still be picked up as a minor version bump.

Maybe instead of a strict "starts with", you could do a regex for feat:|feature: instead.

(If interested I can put up a PR.)

[mikeal]

Sounds good to me, but we’ll need to make sure we can still support the new breaking syntax feat!: and fix!: #26