The 10.9 schema brought a lot of updates to endpoints and deprecated many endpoints. While 10.9 server is 10.8 client compatible, there are issues when a 10.9 generated-schema wants to work with 10.8 server.

Just need to come up with a good time within the 2024 calendar year to make 10.9 servers a minimum, and we should also probably add a badge/indicator to the README for it. Probably do at the same time as the iOS 16 minimum release.

Previous PR for reference: #1072