Update attrs to 21.2.0#511

pyup-bot wants to merge 1 commit intomasterpythonprobr/libpythonpro:masterfrom

pyup-update-attrs-19.1.0-to-21.2.0pythonprobr/libpythonpro:pyup-update-attrs-19.1.0-to-21.2.0Copy head branch name to clipboard