chore: skip unity ci when Fork PR open

Author: guitarrapc

.github/workflows/build-debug.yml

@@ -28,7 +28,7 @@ jobs:
       - run: dotnet test -c Debug --no-build
 
   build-unity:
-    if: "!(contains(github.event.head_commit.message, '[skip ci]') || contains(github.event.head_commit.message, '[ci skip]')) && ((github.event_name == 'push' && github.repository_owner == 'Cysharp') || startsWith(github.event.pull_request.head.label, 'Cysharp:'))"
+    if: "((github.event_name == 'push' && github.repository_owner == 'Cysharp') || startsWith(github.event.pull_request.head.label, 'Cysharp:'))"
     strategy:
       matrix:
         unity: ["2019.3.9f1", "2019.4.13f1", "2020.1.12f1"]