Merge pull request #7917 from docker/dependabot/pip/attrs-20.3.0

Bump attrs from 20.1.0 to 20.3.0

requirements-indirect.txt

@@ -1,6 +1,6 @@
 altgraph==0.17
 appdirs==1.4.4
-attrs==20.1.0
+attrs==20.3.0
 bcrypt==3.1.7
 cffi==1.14.4
 cryptography==3.2.1