GH action: adding prerelease back

Addin the prerelease tag back

Signed-off-by: Flavio Castelli <fcastelli@suse.com>

Author: flavio

.github/workflows/release.yml

@@ -128,7 +128,8 @@ jobs:
               release_id: `${RELEASE_ID}`,
               draft: false,
               tag_name: `${TAG_NAME}`,
-              name: `${TAG_NAME}`
+              name: `${TAG_NAME}`,
+              prerelease: `${{ contains(github.event.workflow_run.head_branch, '-alpha') || contains(github.event.workflow_run.head_branch, '-beta') || contains(github.event.workflow_run.head_branch, '-rc') }}`,
             });
 
       - name: Trigger chart update