Fix config (#703)

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### Summary

Fixes the config so the tests work on my machine.

setup.cfg

@@ -1,2 +1,2 @@
 [metadata]
-description-file = README.md
+description_file = README.md

setup.py

@@ -18,5 +18,5 @@
     packages=setuptools.find_packages(),
     package_data={"ecosystem": ["html_templates/*.jinja"]},
     install_requires=install_requires,
-    python_requires='>=3.6'
+    python_requires='>=3.9'
 )

tox.ini

@@ -4,6 +4,7 @@ envlist = py39, lint, coverage, black
 skipsdist = True
 
 [testenv]
+basepython = python3.9
 usedevelop = true
 passenv = *
 install_command = pip install -U {opts} {packages}