BF: remove dependencies not needed for python >= 3.5

Moreover inclusion of pathlib into list of dependencies breaks on
Debian installation with python 3.7 where there is no explicit pathlib
package available

Author: yarikoptic

heudiconv/info.py

@@ -23,9 +23,7 @@
 REQUIRES = [
     'nibabel',
     'pydicom',
-    'nipype >=1.0.0; python_version > "3.0"',
-    'nipype >=1.0.0,!=1.2.1,!=1.2.2; python_version == "2.7"',
-    'pathlib',
+    'nipype >=1.0.0',
     'dcmstack>=0.8',
     'etelemetry',
     'filelock>=3.0.12',