Prevent go test output being interleaved with python

kitty_tests/main.py

@@ -178,6 +178,8 @@ def run_python_tests(args: Any, go_proc: 'Optional[subprocess.Popen[bytes]]' = N
             if go_proc.wait(0.1) is None:
                 go_proc.kill()
 
+        sys.stdout.flush()
+        sys.stderr.flush()
         print(go_proc.stdout.read().decode('utf-8', 'replace'), end='', flush=True)
         go_proc.stdout.close()
         go_proc.wait()