ci(backport): use major version

This project can easily use the latest release, without having to
explicitly update on each release. This should make it easier to release
more often.

.github/workflows/backport.yml

@@ -25,7 +25,7 @@ jobs:
     steps:
       - uses: actions/checkout@v3
       - name: Create backport PRs
-        uses: zeebe-io/backport-action@v0.0.8
+        uses: zeebe-io/backport-action@v0
         with:
           # Required
           # Token to authenticate requests to GitHub