Fix requirements issue for python 3.6.x

requirements_dev.txt

@@ -15,7 +15,7 @@ svgutils>=0.3.1
 pyarrow>=0.13.0
 pandas>=0.25.1
 importlib-metadata>=0.17
-importlib-resources>=1.0.1
+importlib-resources>=1.0.1,<2
 six>=1.12.0
 timeout-decorator>=0.4.1
 attrs