Change 'bool operator ==(dynamic other))' to 'bool operator ==(Object other))'

[sbergmair]

While using Mockito, there exists an error after running the build_runner concerning the override of the operator.
The override that is used in this package seems to be not correct, because in object.dart of the dart language there is an abstract method like this:
external bool operator ==(Object other);
I think that's why mockito does not find the correct implementation of this override.
There was also an discussion about this: dart-lang/mockito#479

Also consider: With this implementation its ok to compare Version and null; while Object specify the compared value not to be null.

[stefanschaller]

Fixed in : #21

[sanmadjack]

I might be a bit behind, why wouldn't it be desirable to check if a version object is null?

[sbergmair]

Since null safety, this is the correct override for the equals operator: https://api.dart.dev/stable/2.19.2/dart-core/Object/operator_equals.html

Before null safety, it's totally fine to check on null.

[ElanDeyan]

Why we simply not use the bool operator ==(covariant Versión other)? This avoid comparing version objects with non version objects.