[FEATURE] Specify prettier version

[akgoogle]

What would you like to change about the program?
A way to specify the prettier version number.

Why do you think this is a cool idea?
Some node versions don't support prettier v2.x.x. I'd like to use this action with prettier v1.19.1

[creyD]

Good idea! I implemented a test version in a new branch, will test tomorrow!

[creyD]

I implemented it for now, you may test it and I would appreciate feedback!

[akgoogle]

Yeah, after upgrading to v2.2 of your action and specifying prettier_version, it works as intended. Thanks!

        uses: creyD/prettier_action@v2.2
        with:
          prettier_version: "1.19.1"

[creyD]

Great! :)