Bump flutter_lints to 4.0 (flutter#148020)

Follow-up to flutter/packages#6695.

Author: goderbauer

packages/flutter_tools/templates/app/pubspec.yaml.tmpl

@@ -14,7 +14,7 @@ dependencies:
 dev_dependencies:
   flutter_test:
     sdk: flutter
-  flutter_lints: ^3.0.0
+  flutter_lints: ^4.0.0
 
 flutter:
   uses-material-design: true
@@ -80,7 +80,7 @@ dev_dependencies:
   # activated in the `analysis_options.yaml` file located at the root of your
   # package. See that file for information about deactivating specific lint
   # rules and activating additional ones.
-  flutter_lints: ^3.0.0
+  flutter_lints: ^4.0.0
 
 # For information on the generic Dart part of this file, see the
 # following page: https://dart.dev/tools/pub/pubspec

packages/flutter_tools/templates/module/common/pubspec.yaml.tmpl

@@ -31,7 +31,7 @@ dependencies:
 dev_dependencies:
   flutter_test:
     sdk: flutter
-  flutter_lints: ^3.0.0
+  flutter_lints: ^4.0.0
 
 # For information on the generic Dart part of this file, see the
 # following page: https://dart.dev/tools/pub/pubspec

packages/flutter_tools/templates/package/pubspec.yaml.tmpl

@@ -14,7 +14,7 @@ dependencies:
 dev_dependencies:
   flutter_test:
     sdk: flutter
-  flutter_lints: ^3.0.0
+  flutter_lints: ^4.0.0
 
 # For information on the generic Dart part of this file, see the
 # following page: https://dart.dev/tools/pub/pubspec

packages/flutter_tools/templates/package_ffi/pubspec.yaml.tmpl

@@ -15,5 +15,5 @@ dependencies:
 dev_dependencies:
   ffi: ^2.1.0
   ffigen: ^11.0.0
-  flutter_lints: ^3.0.0
+  flutter_lints: ^4.0.0
   test: ^1.24.9

packages/flutter_tools/templates/plugin_shared/pubspec.yaml.tmpl

@@ -24,7 +24,7 @@ dev_dependencies:
 {{/withFfi}}
   flutter_test:
     sdk: flutter
-  flutter_lints: ^3.0.0
+  flutter_lints: ^4.0.0
 
 # For information on the generic Dart part of this file, see the
 # following page: https://dart.dev/tools/pub/pubspec

packages/flutter_tools/templates/skeleton/pubspec.yaml.tmpl

@@ -19,7 +19,7 @@ dev_dependencies:
   flutter_test:
     sdk: flutter
 
-  flutter_lints: ^3.0.0
+  flutter_lints: ^4.0.0
 
 flutter:
   uses-material-design: true