Support pydantic 1.10 (Probably best to support 1.9+)

[segevfiner]

Otherwise having pygls installed prevents using newer pydantic versions due to how Python handles dependencies.

[tombh]

We'll be completely removing Pydantic in the upcoming v1 release #273

[karthiknadig]

https://github.com/openlawlibrary/pygls/pull/280 should address this issue.