CLN: ci code checks
- [ ] closes #xxxx
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

> Do these changes solve an issue

No, it will only solve my obnoxious OCD.

> are you sure they work across platforms / shells?

The thing is, I didn't write anything new, I just saw for example that on one line the ```include``` syntax is used like this:

```
--include "*.pyx" --include "*.py"
```

And on another line, it was used like:

```
--include=*.{py,pyx}
```

Because they're doing the exact same thing, I decided to pick one syntax (The second one just seems more compact), and apply it to every line that uses the ```--include``` flag.