signature mismatch for `__try_update_forward_refs__`

[Mike Lundy]

This MR changed the signature for __try_update_forward_refs__ which unfortunately causes this signature to need to change, too:

pydantic-yaml/pydantic_yaml/mixin.py

Line 264 in 4f698b6

 def __try_update_forward_refs__(cls) -> None: 

(it was retroactively marked a breaking change: https://github.com/pydantic/pydantic/blob/main/HISTORY.md#v191-2022-05-19)

[Anatoly Makarevich]

Fixed in v0.8.1, thanks for reporting!

[Mike Lundy]

Cheers!