package:http2 v3.1.0

• Gracefully handle receiving headers on a stream that the client has canceled. (#1799)
• Treat incoming server push streams as connection protocol error when pushes are disabled (SETTINGS_ENABLE_PUSH=0).
• Enforce the locally advertised SETTINGS_MAX_CONCURRENT_STREAMS limit on incoming remote streams.
• Add Http2Client (package:http2/client.dart), a pooled, multiplexed
  package:http Client backed by HTTP/2 connections.
• Add ClientTransportConnection.peerMaxConcurrentStreams, exposing the peer's
  most recently advertised SETTINGS_MAX_CONCURRENT_STREAMS. Note this is a
  new member on an implementable class, so any existing
  implements ClientTransportConnection will need updating.