Revert "Update how the package gets the version to avoid problem with pkg_resources"

This reverts commit fa563a9f.

enstools/encoding/__init__.py

-# To have the Version number in a single place, there's a VERSION file in the package root directory.
-# Here we read that file.
-from pathlib import Path
-version_file = Path(__file__).resolve().parent.parent.parent / "VERSION"
-__version__ = version_file.read_text().strip()
+# to convert enstools into a namespace package, the version is now listed here and not in the level above
+import pkg_resources  # part of setuptools
+version = pkg_resources.require("enstools-encoding")[0].version
+__version__ = version