chore: add funding and topics to pubspec.yaml (#176)

Author: felangel

pubspec.yaml

@@ -5,6 +5,8 @@ repository: https://github.com/felangel/equatable
 issue_tracker: https://github.com/felangel/equatable/issues
 homepage: https://github.com/felangel/equatable
 documentation: https://github.com/felangel/equatable
+topics: [equality, equals]
+funding: [https://github.com/sponsors/felangel]
 
 environment:
   sdk: ">=2.12.0 <3.0.0"