Bump greenlet to 3.0.* (#10833)

Author: Daverball

stubs/greenlet/METADATA.toml

@@ -1,2 +1,2 @@
-version = "2.0.*"
+version = "3.0.*"
 upstream_repository = "https://github.com/python-greenlet/greenlet"

stubs/greenlet/greenlet/_greenlet.pyi

@@ -63,6 +63,10 @@ class greenlet:
     @staticmethod
     def settrace(__callback: _TraceCallback | None) -> _TraceCallback | None: ...
 
+class UnswitchableGreenlet(greenlet):  # undocumented
+    force_switch_error: bool
+    force_slp_switch_error: bool
+
 def enable_optional_cleanup(__enabled: bool) -> None: ...
 def get_clocks_used_doing_optional_cleanup() -> int: ...
 def get_pending_cleanup_count() -> int: ...