Update flake8-quotes from 2.0.1 to 2.1.0

Author: pyup-bot

dev-requirements.txt

@@ -5,7 +5,7 @@ doc8==0.8.0
 dodgy==0.1.9  # Look for uploaded secrets
 dulwich==0.19.11
 flake8-commas==2.0.0  # Require silicon valley commas
-flake8-quotes==2.0.1  # Require single quotes
+flake8-quotes==2.1.0  # Require single quotes
 flake8==3.7.8  # Lint
 freezegun==0.3.12
 isort==4.3.21  # Lint imports