[ty] Update CONFORMANCE_SUITE_COMMIT to new hash (#23276)
## Summary
<!-- What's the purpose of the change? What does it do, and why? -->
Bring in upstream conformance suite changes:
https://github.com/python/typing/compare/f98d75ebb241d6f49e1a985a4f259f46b2056626...ffd520acd116aacbbba793c8f1f1fd51dfda83ae
## Test Plan
<!-- How was it tested? -->
CI conformance job 🟢
