Allow the usage of multiple requests versions. (#55)

Author: LKaemmerling

setup.py

@@ -14,7 +14,7 @@
 requirements = [
     "future==0.17.1",
     "python-dateutil==2.7.5",
-    "requests==2.20.0"
+    "requests>=2.20,<2.23"
 ]
 
 extras_require = {