[tests] use a tuple type for the utils module __all__ module declarat…

…ion.

Ref: https://github.com/python/typing/blob/9a39406fa45fbfa76eb5d35afb7863f5f727ad87/docs/source/libraries.rst?plain=1#L108-L119

Co-authored-by: Chris Sewell <[email protected]>

tests/utils.py

@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-__all__ = ["http_server"]
+__all__ = ("http_server",)
 
 from contextlib import contextmanager
 from http.server import ThreadingHTTPServer