Increase the usage of augmented assignment statements

### Description
:eyes: Some source code analysis tools can help to find opportunities for improving software components.
:thought_balloon: I propose to [increase the usage of augmented assignment statements](https://docs.python.org/3/reference/simple_stmts.html#augmented-assignment-statements "Augmented assignment statements") accordingly.

### Additional context
Would you like to integrate anything from a transformation result which can be generated by a command like the following?
(:point_right: Please check also for questionable change suggestions because of an evolving search pattern.)
```
lokal$ perl -p -i.orig -0777 -e 's/^(?\s+)(?\S+)\s*=\s*\k[ \t]*(?[+\-%&|^@]|\*\*?|\/\/?|<<|>>)/$+{indentation}$+{target} $+{operator}=/gm' $(find ~/Projekte/Astropy/lokal -name '*.py')
```

Review the proposed Perl transformation and the Python files matched by `find ~/Projekte/Astropy/lokal -name '*.py'`. Check each suggested change for correctness as the search pattern evolves, then verify that only appropriate augmented assignments are introduced and questionable suggestions are excluded.

Written by the indexing model from the issue text.