python: Replace universal_newlines with text.

This is supported in Python ≥ 3.7.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

tools/test-queue-worker-reload

@@ -66,7 +66,7 @@ if __name__ == "__main__":
         bufsize=1,  # line buffered
         stdout=subprocess.PIPE,
         stderr=subprocess.STDOUT,
-        universal_newlines=True,
+        text=True,
     )
     failed = check_worker_launch(run_dev)