fix(projects): missing abc when using python 3.10
Summary:
This PR is a small  fix of `AttributeError` when using python3.10
User could reproduce by using the following code
```
import importlib
type(importlib.abc.MetaPathFinder)
```
PTAL ppwwyyxx
Pull Request resolved:
# Copyright (c) Facebook, Inc. and its affiliates.
-import importlib
+import importlib.abc
+import importlib.util
from pathlib import Path
+__all__ = []
+
_PROJECTS = {
"point_rend": "PointRend",
"deeplab": "DeepLab",
