fix python version check for typing import

[baudsimVD]

Running dbt-osmosis on python 3.9 results in the following error :
AttributeError: module 'typing' has no attribute 'ParamSpec'

Also switching to typing.Union in osmosis.py, it was throwing :

python3.9/site-packages/dbt_osmosis/core/osmosis.py", line 1096, in _get_yaml_path_template
    path_template = _find_first(t.cast(list[str | None], conf), lambda v: v is not None)
TypeError: unsupported operand type(s) for |: 'type' and 'NoneType'

I tested the refactor command and it works fine after those modifications

[z3z1ma]

Ah good catch. Thanks! I see we don't test on 3.9 in the test suite. Not entirely sure why. Can probably add it.