refactor: update to Dart 3 and Very Good Analysis 5 (#48)

Author: renancaraujo

pubspec.yaml

@@ -4,7 +4,7 @@ version: 0.3.0
 homepage: https://github.com/VeryGoodOpenSource/pub_updater
 
 environment:
-  sdk: ">=2.12.0 <3.0.0"
+  sdk: ">=3.0.0 <4.0.0"
 
 dependencies:
   http: ^1.0.0
@@ -17,4 +17,4 @@ dev_dependencies:
   json_serializable: ^6.5.3
   mocktail: ^0.3.0
   test: ^1.17.0
-  very_good_analysis: ^4.0.0
+  very_good_analysis: ^5.0.0

test/pub_update_test.dart

@@ -15,8 +15,6 @@ class MockResponse extends Mock implements Response {}
 
 class MockProcessManager extends Mock implements ProcessManager {}
 
-class FakeProcessResult extends Fake implements ProcessResult {}
-
 const emptyResponseBody = '{}';
 
 const command = [
@@ -59,7 +57,7 @@ void main() {
       when(() => response.body).thenReturn(validPackageInfoResponseBody);
 
       when(() => processManager.run(any()))
-          .thenAnswer((_) => Future.value(FakeProcessResult()));
+          .thenAnswer((_) => Future.value(ProcessResult(42, 0, '', '')));
     });
 
     test('can be instantiated without an explicit http client', () {
@@ -155,7 +153,7 @@ void main() {
               .thenReturn(preReleasePackageInfoResponseBody);
 
           when(() => processManager.run(any()))
-              .thenAnswer((_) => Future.value(FakeProcessResult()));
+              .thenAnswer((_) => Future.value(ProcessResult(42, 0, '', '')));
         });
 
         test('returns false when currentVersion < latestVersion', () async {