Fix py2 testing error due to PR #998 in nrn.

Jaquier Aurélien Tristan · Jaquier Aurélien Tristan · commit 94e7f9015d7e · 2021-02-22T17:56:13.000+01:00
diff --git a/tox.ini b/tox.ini
@@ -17,6 +17,7 @@ deps =
     mock
     nose
     sh
+    pathlib
 download = true
 whitelist_externals =
     make
