py-pygls: update to 1.2.0.

What's Changed

    Remove dependency on typeguard by @karthiknadig in #411
    Simplify vscode-playground setup and fix Python discovery by @alcarney in #374
    chore: pin lsprotocol to 2023.0.0 by @alcarney in #414
    build: v1.2.0 by @tombh in #412

(wiz)