Allow restore_payload to reconstruct bodies for non-POST methods

[azhar22k]

Motivation

Fixes #41.

restore_payload() previously checked if request.method != "POST": return data. For any other method that carries a form or multipart body — such as PUT and PATCH — Werkzeug consumes the body stream into request.form and request.files, leaving request.data empty (b""). Consequently, restore_payload() returned an empty bytes object, silently dropping the body when proxying requests (e.g., in LocalStack API Gateway HTTP API v2 / Lambda integrations).

Per RFC 9110, HTTP methods like PUT and PATCH can legitimately carry any representation including multipart/form-data and application/x-www-form-urlencoded.

Changes

• Removed the request.method != "POST" early-return in restore_payload(), allowing form and multipart body reconstruction regardless of HTTP method.
• Improved multipart boundary extraction by querying request.mimetype_params.get("boundary"), gracefully handling boundaries with quoted strings or additional parameters (such as charset).
• Parametrized multipart and form-urlencoded payload restoration tests across POST, PUT, and PATCH in tests/test_request.py.
• Added a test in tests/test_request.py verifying boundary parsing when the Content-Type header contains extra parameters and quotes.

Testing

• Verified reproduction script from restore_payload drops the body of multipart/form-data and x-www-form-urlencoded PUT/PATCH requests #41: PUT and PATCH requests with multipart/form-data and application/x-www-form-urlencoded now properly reconstruct the payload instead of returning empty bytes.
• All 173 pytest tests pass (make test).
• Code formatted and linted with make format and make lint.

[bentsku]

This is a great change! Thanks a lot for addressing the issue. I just have a question about removing the method check completely, in order to not add new regressions. Once this is addressed, I think we'd be good to go?

[azhar22k]

Addressed in 17b9064: updated restore_payload to check if request.method not in ("POST", "PUT", "PATCH"): return data, and added test coverage for non-body methods (GET, DELETE, etc.). All tests and linters pass!