Increase template Swift version from 4 to 5 (#41882)

diff --git a/packages/flutter_tools/test/general.shard/macos/cocoapods_test.dart b/packages/flutter_tools/test/general.shard/macos/cocoapods_test.dart
index f4079cd..5d058e7 100644
--- a/packages/flutter_tools/test/general.shard/macos/cocoapods_test.dart
+++ b/packages/flutter_tools/test/general.shard/macos/cocoapods_test.dart
@@ -186,7 +186,7 @@
       when(mockXcodeProjectInterpreter.isInstalled).thenReturn(true);
       when(mockXcodeProjectInterpreter.getBuildSettings(any, any))
         .thenAnswer((_) async => <String, String>{
-          'SWIFT_VERSION': '4.0',
+          'SWIFT_VERSION': '5.0',
         });
 
       final FlutterProject project = FlutterProject.fromPath('project');