fix: error checking type for "subscripted generics"

[mikeshultz]

What I did

Fixes the error:

[...snip...]
  File "/home/mike/.venvs/silverback-cluster/lib/python3.11/site-packages/silverback/recorder.py", line 91, in from_taskiq
    metrics=cls._extract_custom_metrics(result.return_value, task_name),
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/mike/.venvs/silverback-cluster/lib/python3.11/site-packages/silverback/recorder.py", line 45, in _extract_custom_metrics
    elif isinstance(result, ScalarType):  # type: ignore[arg-type,misc]
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/typing.py", line 1689, in __instancecheck__
    return self.__subclasscheck__(type(obj))
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/typing.py", line 1693, in __subclasscheck__
    if issubclass(cls, arg):
       ^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/typing.py", line 1315, in __subclasscheck__
    raise TypeError("Subscripted generics cannot be used with"
TypeError: Subscripted generics cannot be used with class and instance checks

Checklist

• Passes all linting checks (pre-commit and CI jobs)
• New test cases have been added and are passing
• Documentation has been updated
• PR title follows Conventional Commit standard (will be automatically included in the changelog)

[fubuloubu]

@mikeshultz this is actually kinda interesting, it will "auto-parse" values outside the INT96 range as Decimal, which can actually be (less efficiently) encoded by Parquet, avoiding raising a bug about it!

[fubuloubu]

In [14]: Datapoints(root={"return_value": 1324})
Out[14]: Datapoints(root={'return_value': ScalarDatapoint(type='scalar', data=1324)})

In [15]: Datapoints(root={"return_value": 2**291})
Out[15]: Datapoints(root={'return_value': ScalarDatapoint(type='scalar', data=Decimal('3978585891278293137243057985174566720803649206378781739523711815145275976100267004264448'))})