Fix CI triggers: v0.5 branch and v* tags only

Author: penberg

.github/workflows/CI.yml

@@ -3,11 +3,9 @@ name: CI
 on:
   push:
     branches:
-      - main
       - v0.5
-    tags-ignore:
-      - '**'
-  pull_request:
+    tags:
+      - 'v*'
 
 permissions:
   contents: write