chore: update README (#143)

We released a new version with v13 so update autodoc

Author: jd

README.md

@@ -11,7 +11,7 @@ More information on https://mergify.com
 
 <!-- AUTO-DOC-INPUT:START - Do not remove or modify this section -->
 ```yaml
-- uses: Mergifyio/gha-mergify-ci@v12
+- uses: Mergifyio/gha-mergify-ci@v13
   id: gha-mergify-ci
   with:
     # The Mergify CI action: