Denial of Service via HTTP/2 CONTINUATION Frames

Early versions of amphp/http-client with HTTP/2 support v4.0.0-rc10 to 4.0.0 will collect HTTP/2 CONTINUATION frames in an unbounded buffer and will not check the header size limit until it has received the ENDHEADERS flag, resulting in an OOM crash. Later versions of amphp/http-client v4.1.0-rc1...