DOC: Drop setuptools from listed dependencies, add importlib-resources

Author: effigies

doc/source/installation.rst

@@ -86,7 +86,7 @@ Requirements
 *  Python_ 3.8 or greater
 *  NumPy_ 1.19 or greater
 *  Packaging_ 17.0 or greater
-*  Setuptools_
+*  importlib-resources_ 1.3 or greater (or Python 3.9+)
 *  SciPy_ (optional, for full SPM-ANALYZE support)
 *  h5py_ (optional, for MINC2 support)
 *  PyDICOM_ 1.0.0 or greater (optional, for DICOM support)

doc/source/links_names.txt

@@ -114,6 +114,7 @@
 .. _python imaging library: https://pypi.python.org/pypi/Pillow
 .. _h5py: https://www.h5py.org/
 .. _packaging: https://packaging.pypa.io
+.. _importlib-resources: https://importlib-resources.readthedocs.io/
 
 .. Python imaging projects
 .. _PyMVPA: http://www.pymvpa.org