Adding PATCH method to environ_add_POST

[Wesleyzxc]

Link to function: https://github.com/Pylons/webob/blob/main/src/webob/request.py#L1554

In the function environ_add_POST, it doesn't seem to consider the PATCH method and is defaulting to POST even on PATCH. Should there be an additional PATCH method in the check?

    if env["REQUEST_METHOD"] not in ("POST", "PUT"):
        env["REQUEST_METHOD"] = "POST"