tagging tests with kdbx3 and kdbx4

test/kdbx4_test.dart

@@ -1,3 +1,5 @@
+@Tags(['kdbx4'])
+
 import 'dart:io';
 
 import 'package:kdbx/kdbx.dart';

test/kdbx_binaries_test.dart

@@ -122,7 +122,7 @@ void main() {
       // make sure the file can still be saved.
       await file.save();
     });
-  });
+  }, tags: ['kdbx3']);
   group('kdbx4 attachment', () {
     test('read binary', () async {
       final file =
@@ -171,7 +171,7 @@ void main() {
     test('Add new attachment kdbx4', () async {
       await _testAddNewAttachment('test/keepass2kdbx4binaries.kdbx');
     });
-  });
+  }, tags: ['kdbx4']);
 }
 
 class IsUtf8String extends CustomMatcher {

test/kdbx_history_test.dart

@@ -97,5 +97,5 @@ void main() {
       await pumpEventQueue();
       dirtyExpect.expectFinished();
     });
-  });
+  }, tags: ['kdbx3']);
 }

test/kdbx_test.dart

@@ -1,3 +1,5 @@
+@Tags(['kdbx3'])
+
 import 'dart:io';
 
 import 'package:kdbx/kdbx.dart';

test/kdbx_upgrade_test.dart

@@ -1,3 +1,5 @@
+@Tags(['kdbx3', 'kdbx4'])
+
 import 'package:kdbx/kdbx.dart';
 import 'package:kdbx/src/kdbx_header.dart';
 import 'package:test/test.dart';