2.0.0 Beta 1

• PHP 8.1 is now required
• Renamed Status and Message to HttpStatus and HttpMessage respectively. Aliases of the old names to the new names exist in this beta version, but may be removed before the stable release
• Added a message parameter to Http2Processor::handleShutdown()
• Http2Parser constructor now requires an HPack instance to be injected, as well as providing parameters for upgrade settings, header size limit, and frame size limits
• Http2Parser::parse() was removed; Http2Parser now has a push() and cancel() methods to push received data and end parsing