Merge pull request #44 from Anselmoo/dependabot/pip/attrs-21.2.0

Bump attrs from 20.3.0 to 21.2.0

Author: Anselmoo

dev-requirements.txt

@@ -7,7 +7,7 @@
 
 # -i https://pypi.org/simple
 appdirs==1.4.4
-attrs==20.3.0; python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'
+attrs==21.2.0; python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'
 black==20.8b1
 click==7.1.2; python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3, 3.4'
 coverage==5.3.1