bump google.golang.org/grpc v1.23.1

full diff: https://github.com/grpc/grpc-go/compare/v1.23.0...v1.23.1

- grpc/grpc-go#3018 server: set and advertise max frame size of 16KB
- grpc/grpc-go#3017 grpclb: fix deadlock in grpclb connection cache
    - Before the fix, if the timer to remove a SubConn fires at the
      same time NewSubConn cancels the timer, it caused a mutex leak
      and deadlock.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

vendor/google.golang.org/grpc/internal/transport/http2_server.go

@@ -138,7 +138,10 @@ func newHTTP2Server(conn net.Conn, config *ServerConfig) (_ ServerTransport, err
 	}
 	framer := newFramer(conn, writeBufSize, readBufSize, maxHeaderListSize)
 	// Send initial settings as connection preface to client.
-	var isettings []http2.Setting
+	isettings := []http2.Setting{{
+		ID:  http2.SettingMaxFrameSize,
+		Val: http2MaxFrameLen,
+	}}
 	// TODO(zhaoq): Have a better way to signal "no limit" because 0 is
 	// permitted in the HTTP2 spec.
 	maxStreams := config.MaxStreams

vendor/google.golang.org/grpc/internal/transport/http_util.go

@@ -667,6 +667,7 @@ func newFramer(conn net.Conn, writeBufferSize, readBufferSize int, maxHeaderList
 		writer: w,
 		fr:     http2.NewFramer(w, r),
 	}
+	f.fr.SetMaxReadFrameSize(http2MaxFrameLen)
 	// Opt-in to Frame reuse API on framer to reduce garbage.
 	// Frames aren't safe to read from after a subsequent call to ReadFrame.
 	f.fr.SetReuseFrames()