Check for self.generic_visit(node) being called in AST visitors.

[lensvol]

I have made things!

Checklist

• I have double checked that there are no unrelated changes in this pull request (old patches, accidental config files, etc)
• I have created at least one test case for the changes I have made
• I have updated the documentation for the changes I have made
• I have added my changes to the CHANGELOG.md

Related issues

Closes #1363.

I've decided not to create tests for that one, since it would be a disproportionally bigger amount of work in my opinion. Open to discussion on that one.

🙏 Please, if you or your company is finding wemake-python-styleguide valuable, help us sustain the project by sponsoring it transparently on https://opencollective.com/wemake-python-styleguide. As a thank you, your profile/company logo will be added to our main README which receives hundreds of unique visitors per day.

[sobolevn]

See python-poetry/poetry#3140

[codecov]

Codecov Report

Merging #1660 into master will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##            master     #1660    +/-   ##
==========================================
  Coverage   100.00%   100.00%            
==========================================
  Files          101       105     +4     
  Lines         5287      5610   +323     
  Branches      1182      1272    +90     
==========================================
+ Hits          5287      5610   +323     

Impacted Files	Coverage Δ
...ython_styleguide/visitors/ast/complexity/counts.py	100.00% <100.00%> (ø)
...thon_styleguide/visitors/ast/complexity/imports.py	100.00% <100.00%> (ø)
wemake_python_styleguide/logic/tree/ifs.py	100.00% <0.00%> (ø)
wemake_python_styleguide/logic/tree/keywords.py	100.00% <0.00%> (ø)
wemake_python_styleguide/logic/tree/variables.py	100.00% <0.00%> (ø)
wemake_python_styleguide/violations/refactoring.py	100.00% <0.00%> (ø)
...emake_python_styleguide/visitors/ast/conditions.py	100.00% <0.00%> (ø)
wemake_python_styleguide/formatter.py	100.00% <0.00%> (ø)
wemake_python_styleguide/version.py	100.00% <0.00%> (ø)
wemake_python_styleguide/checker.py	100.00% <0.00%> (ø)
... and 1 more

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[sobolevn]

I knew we have some items missing! Thanks a lot! 👍