Update dependency six to v1.16.0

Author: renovate-bot

requirements.txt

@@ -18,7 +18,7 @@ pytest==6.0.1
 rdflib==5.0.0
 rdflib-jsonld==0.5.0
 requests==2.24.0
-six==1.15.0
+six==1.16.0
 soupsieve==2.0.1
 urllib3==1.25.10
 w3lib==1.22.0