Remove hard limit on request size

[dhalbert]

As #4 points out, the request size can't grow.

[karlfl]

Could this be done via a property with a setter on the HTTPServer class? That would allow flexibility for the developers without changing the API for constructing an instance of the HTTPServer class.

For example, we could add the following to the end of the HTTPServer class:

    def RequestBufferSize(self) -> int:
        """
        The maximum size of the request buffer.  Set this after creating the server instance
        Defaults size is 1024 bytes.
        Example::
            server = HTTPServer(pool)
            server.RequestSize = 2048
            ...
            server.serve_forever(str(wifi.radio.ipv4_address))
        """
        return len(self._buffer)

    @RequestBufferSize.setter
    def RequestSize(self, value: int) -> None:
        self._buffer = bytearray(value)