minor #18327 Enable new DOCtor rule no_duplicate_use_statements (OskarStark)

This PR was merged into the 5.4 branch.

Discussion
----------

Enable new DOCtor rule `no_duplicate_use_statements`

cc `@alamirault`

Commits
-------

e32ee28 Enable new DOCtor rule `no_duplicate_use_statements`

Author: OskarStark

.doctor-rst.yaml

@@ -34,6 +34,7 @@ rules:
     no_brackets_in_method_directive: ~
     no_composer_req: ~
     no_directive_after_shorthand: ~
+    no_duplicate_use_statements: ~
     no_explicit_use_of_code_block_php: ~
     no_inheritdoc: ~
     no_merge_conflict: ~