Do not yield to body emit backpressure

This yield blocked data on other streams from being processed.

src/Connection/Http2Connection.php

@@ -650,7 +650,7 @@ private function parser(): \Generator
                             }
 
                             if (isset($this->bodyEmitters[$id])) { // Stream may close while reading body chunk.
-                                yield $this->bodyEmitters[$id]->emit($body);
+                                $this->bodyEmitters[$id]->emit($body);
                             }
                         }