replace setup.py,cfg with pyproject.toml

- fix #385
- use pyproject.toml instead of setup.py (note: may need to change README for PyPi to exclude
  banners)
- remove versioneer and use versioningit (use alchemlyb.__version__ directly where
  the version is needed, e.g., for sphinx docs)
- updated CHANGES for 2.4.0

pyproject.toml

@@ -50,7 +50,7 @@ dependencies = [
 	     "matplotlib>=3.7",
 	     "loguru",
 	     "pyarrow",
-         "joblib",
+             "joblib",
 ]