Use f-strings

Co-authored-by: Leander Stephen D'Souza <leanderdsouza1234@gmail.com>

Author: cottsay

colcon_mixin/mixin/repository.py

@@ -37,7 +37,7 @@ def __getattr__(name):
                 "get_mixin_repositories_file()' instead", stacklevel=2)
             return get_mixin_repositories_file()
         raise AttributeError(
-            "module '%s' has no attribute '%s'" % (__name__, name))
+            f"module '{__name__}' has no attribute '{name}'")
 else:
     # for backward compatibility but without a deprecation warning on usage
     """The path of the yaml file describing the mixin repositories."""