pytest_httpserver/httpserver.py: make mypy compatible with werkzeug 3.0.0

In werkzeug 3.0.0 they removed the attributes which were previously
announced, but mypy complains about this, even if I add hasattr() check.

This is the error thrown by mypy:
```
pytest_httpserver/httpserver.py:139: error: Module has no attribute "parse_authorization_header"; maybe "parse_options_header"?
```

I tried with `assert` and `if`, both with getattr and hasattr checks but
none of these worked.

Author: csernazs

pytest_httpserver/httpserver.py

@@ -136,7 +136,7 @@ def __init__(self, matchers: Optional[Mapping[str, Callable[[Optional[str], str]
     def authorization_header_value_matcher(actual: Optional[str], expected: str) -> bool:
         callable = getattr(Authorization, "from_header", None)
         if callable is None:  # Werkzeug < 2.3.0
-            callable = werkzeug.http.parse_authorization_header
+            callable = werkzeug.http.parse_authorization_header  # type: ignore[attr-defined]
         return callable(actual) == callable(expected)
 
     @staticmethod