ci(action): Don't block merges during first and second RC of major releases

Signed-off-by: Joas Schilling <coding@schilljs.com>

Author: nickvergessen

.github/workflows/block-merge-freeze.yml

@@ -54,4 +54,4 @@ jobs:
 
       - name: Run check
         if: ${{ env.server_ref != '' }}
-        run: cat version.php | grep 'OC_VersionString' | grep -i -v 'RC'
+        run: cat version.php | grep 'OC_VersionString' | grep -i -v -E '(\.0 RC[3-9]|\.[1-9][0-9]* RC)'