update all vendored dependencies

vendor/google.golang.org/grpc/transport/go16.go

@@ -22,6 +22,7 @@ package transport
 
 import (
 	"net"
+	"net/http"
 
 	"google.golang.org/grpc/codes"
 
@@ -43,3 +44,8 @@ func ContextErr(err error) StreamError {
 	}
 	return streamErrorf(codes.Internal, "Unexpected error from context packet: %v", err)
 }
+
+// contextFromRequest returns a background context.
+func contextFromRequest(r *http.Request) context.Context {
+	return context.Background()
+}