overlayfs requires python3.10+

[ap--]

Hello everyone,

I noticed that the morefs package requires python3.8+ but overlayfs isn't 3.8 and 3.9 compatible:

❯ python3.8 -m venv venv38
❯ source venv38/bin/activate
❯ pip install morefs
...
Successfully installed fsspec-2024.6.1 morefs-0.2.1

❯ python -c "import fsspec; fsspec.get_filesystem_class('overlayfs')"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/home/poehlmann/morefs_err/venv38/lib/python3.8/site-packages/fsspec/registry.py", line 242, in get_filesystem_class
    register_implementation(protocol, _import_class(bit["class"]))
  File "/home/poehlmann/morefs_err/venv38/lib/python3.8/site-packages/fsspec/registry.py", line 277, in _import_class
    mod = importlib.import_module(mod)
  File "/usr/lib/python3.8/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 843, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/home/poehlmann/morefs_err/venv38/lib/python3.8/site-packages/morefs/overlay.py", line 9, in <module>
    class OverlayFileSystem(fsspec.AbstractFileSystem):  # pylint: disable=abstract-method
  File "/home/poehlmann/morefs_err/venv38/lib/python3.8/site-packages/morefs/overlay.py", line 81, in OverlayFileSystem
    info = _iterate_fs_with("info")  # pylint: disable=no-value-for-parameter
TypeError: 'staticmethod' object is not callable

It works for python3.10+

❯ python3.10 -m venv venv310
❯ source venv310/bin/activate
❯ pip install morefs
...
Successfully installed fsspec-2024.6.1 morefs-0.2.1

❯ python -c "import fsspec; fsspec.get_filesystem_class('overlayfs')"

The staticmethod behavior changed in Python3.10: python/cpython#87848

I'll prepare a PR right away.

-Andreas