[CI] Fix formatting in announce regex

Author: robotgryphon

.github/workflows/announce-latest-nightly.yml

@@ -45,7 +45,7 @@ jobs:
           owner: compactmods
           repo: compactmachines
           group: dev.compactmods.compactmachines
-          filter: "^compactmachines-(?:[\\d\\.]{4})\.jar$"
+          filter: "^compactmachines-(?:[\\d\\.]{4}).jar$"
           outputFile: compactmachines-nightly.json
 
       - name: Debug output