Update to Steamworks SDK 1.60

[rlabrecque]

Tracking issue

Release notes
https://store.steampowered.com/news/group/4145017?emclan=103582791433666425&emgid=6489204638529587038

[MigrantP]

Looking forward to this, the timeline integration looks like a nice thing to integrate!

[rlabrecque]

This should be usable with the https://github.com/rlabrecque/Steamworks.NET/tree/rlabrecque/update-to-1.60 branch in #623; I'm working on upgrading Steamworks.NET-Test and Example before I merge it in to main though; should be within the next couple days.

Edit: I ended up merging this to main to make iterating on Steamworks.NET-Test and Example easier since they are both using the Unity package manager.

[rlabrecque]

Funny story; calling GetNumBetas crashes Steam because it's not supposed to be called from outside of the Steam process. 🙈