Create the wiki if it was not initialised before

Hi !

Here is (IMHO) an interesting feature request for your action : Add the ability to initiate the Repo's wiki if there is no wiki in it.

Actually, when you use your action on a repo with no wiki initialised, you'll get the following error : `remote error: access denied or repository not exported: /c/nw/cc/50/e1/252169893/XXXXXXXX.wiki.git`

It could be great to check this error and create the wiki (with an API call or another action for example) to initiate the wiki then retry to run the `git pull/push` of the wiki.