Alternative syntax for unions requires Python 3.10 or newer

Argument of type "(self: Self@MultiFidelityStrategy) -> None" cannot be assigned to parameter of type "_AnyModelAfterValidator[_ModelType@model_validator]"   Type "(self: Self@MultiFidelityStrategy) -> None" cannot be assigned to type "_AnyModelAfterValidator[_ModelType@model_validator]"     Type "(self: Self@MultiFidelityStrategy) -> None" cannot be assigned to type "(_ModelType@model_validator, ValidationInfo) -> _ModelType@model_validator"       Function accepts too many positional parameters; expected 1 but received 2         Parameter 1: type "_ModelType@model_validator" cannot be assigned to type "Self@MultiFidelityStrategy"           "object*" is incompatible with "MultiFidelityStrategy"     Type "(self: Self@MultiFidelityStrategy) -> None" cannot be assigned to type "(_ModelType@model_validator) -> _ModelType@model_validator"       Parameter 1: type "_ModelType@model_validator" cannot be assigned to type "Self@MultiFidelityStrategy"         "object*" is incompatible with "MultiFidelityStrategy" (reportGeneralTypeIssues)