Ensure setuptools via PEP508/518 pyproject.toml


diff --git a/setup.cfg b/setup.cfg
index 0b6c813..33ab5f7 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -30,3 +30,7 @@
 
 [options]
 python_requires = >= 3.5.2
+
+[options.extras_require]
+progress =
+  tqdm
\ No newline at end of file