ci(all): fix analysis issues

Author: FatulM

example/test/sealed/nullsafe/data/generic/result_single_2_test.dart

@@ -20,6 +20,7 @@ void main() {
 
       final d = ResultSuccess(data: null);
       expect(d.data, isNull);
+      // ignore: prefer_void_to_null
       expect(d, hasType<ResultSuccess<Null>>());
     });
 

example/test/sealed/nullsafe/data/generic/result_single_4_test.dart

@@ -20,6 +20,7 @@ void main() {
 
       final d = ResultSuccess(data: null);
       expect(d.data, isNull);
+      // ignore: prefer_void_to_null
       expect(d, hasType<ResultSuccess<Null>>());
     });