Skip Podfile change on non-macOS platforms.

The Podfile is only generated on a macOS host.

Author: IVLIVS-III

script/tool/lib/src/create_all_plugins_app_command.dart

@@ -288,6 +288,11 @@ dev_dependencies:${_pubspecMapString(pubspec.devDependencies)}
   }
 
   Future<void> _updateMacosPodfile() async {
+    // Only change the macOS deployment target if the host platform is macOS.
+    if (!io.Platform.isMacOS) {
+      return;
+    }
+
     final File podfileFile =
         app.platformDirectory(FlutterPlatform.macos).childFile('Podfile');
     if (!podfileFile.existsSync()) {

script/tool/test/create_all_plugins_app_command_test.dart

@@ -103,23 +103,28 @@ void main() {
           baselinePubspec.environment?[dartSdkKey]);
     });
 
-    test('macOS deployment target is modified', () async {
+    test('macOS deployment target is modified in Podfile', () async {
       await runCapturingPrint(runner, <String>['all-plugins-app']);
-
       final List<String> podfile = command.app
           .platformDirectory(FlutterPlatform.macos)
           .childFile('Podfile')
           .readAsLinesSync();
-      final List<String> pbxproj = command.app
-          .platformDirectory(FlutterPlatform.macos)
-          .childDirectory('Runner.xcodeproj')
-          .childFile('project.pbxproj')
-          .readAsLinesSync();
 
       expect(
           podfile,
           everyElement((String line) =>
               !line.contains('platform :osx') || line.contains("'10.15'")));
+    },
+        // Podfile is only generated on macOS.
+        skip: !io.Platform.isMacOS);
+
+    test('macOS deployment target is modified in pbxproj', () async {
+      await runCapturingPrint(runner, <String>['all-plugins-app']);
+      final List<String> pbxproj = command.app
+          .platformDirectory(FlutterPlatform.macos)
+          .childDirectory('Runner.xcodeproj')
+          .childFile('project.pbxproj')
+          .readAsLinesSync();
 
       expect(
           pbxproj,