chore: Ignore fsspec [import-untyped] (#210)

```py
_fs.pyi:18: error: Skipping analyzing "fsspec": module is installed, but missing library stubs or py.typed marker  [import-untyped]
_fs.pyi:18: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports Found 1 error in 1 file (checked 64 source files)
```

- fsspec/filesystem_spec#625
- fsspec/filesystem_spec#1676

Author: dangotbanned

pyarrow-stubs/_fs.pyi

@@ -15,7 +15,7 @@ else:
 
 from typing import Union, overload
 
-from fsspec import AbstractFileSystem
+from fsspec import AbstractFileSystem  # type: ignore[import-untyped]
 
 from .lib import NativeFile, _Weakrefable