4.1.x-alpha-release: update tag-filter

Author: michaelklishin

.github/workflows/4.1.x-alpha-release.yml

@@ -30,5 +30,5 @@ jobs:
         with:
           repository: "rabbitmq/server-packages"
           token: ${{ secrets.MK_RELEASE_AUTOMATION_TOKEN }}
-          tag-filter: '^v4.1.0-alpha\..+$'
+          tag-filter: '^prerelease\.alphas.\..+$'
           keep-last-n: 4