Whitespace is not stripped from the right side of header values, as the RFCs require #47

Description

The HTTP RFC ABNF states that spaces and tabs on either side of header values are not to be considered part of the header value.

When protocol-http1 receives a request with spaces or tabs on the right side of a header value, it does not strip that whitespace.

This is in contrast to the behavior of nearly all other popular HTTP implementations.

Reproduction Steps

0. Run a protocol-http1 web server that echoes back received header values, like this one.
1. Send it a request with a header containing whitespace, and observe the response:

printf 'GET / HTTP/1.1\r\nHost: a \r\n\r\n' \
    | timeout 1 ncat localhost 80 \
    | grep '"headers"' \
    | jq .headers[0][1] \
    | xargs echo \
    | base64 -d \
    | od -tcx1

0000000   a
         61  20
0000002

The trailing space (0x20) persists in the parsed header value.