Don't check the formatting of ffigened code (#1010)

Author: brianquinlan

.github/workflows/cupertino.yml

@@ -36,7 +36,14 @@ jobs:
         name: Install dependencies
         run: flutter pub get
       - name: Check formatting
-        run: dart format --output=none --set-exit-if-changed .
+        # Don't lint the generated file native_cupertino_bindings.dart
+        # This approach is simpler than using `find` and excluding that file
+        # because `dart format` also excludes other file e.g. ones in
+        # directories start with '.'.
+        run: >
+          mv lib/src/native_cupertino_bindings.dart lib/src/native_cupertino_bindings.tmp &&
+          dart format --output=none --set-exit-if-changed . &&
+          mv lib/src/native_cupertino_bindings.tmp lib/src/native_cupertino_bindings.dart
         if: always() && steps.install.outcome == 'success'
       - name: Analyze code
         run: flutter analyze --fatal-infos