Merge branch 'bump-responses' into 'master'

Bump Python requirement responses to 0.21.0

See merge request teklia/arkindex/backend!1713

tests-requirements.txt

 coverage==6.4.4
 django-nose==1.4.7
 moto[s3]==3.1.12
-responses==0.20.0
+responses==0.21.0
 tripoli==2.0.0