fix: adjust itertools.chain to use from iterable in release-demo

Author: 56kyle

scripts/release-demo.py

@@ -81,7 +81,7 @@ def _create_demo_release_pr() -> None:
         "--assignee": "@me",
         "--base": "main",
     }
-    command: list[str] = ["gh", "pr", "create", *itertools.chain(pr_kwargs.items())]
+    command: list[str] = ["gh", "pr", "create", *itertools.chain.from_iterable(pr_kwargs.items())]
     subprocess.run(command, check=True)