TYP: use OpsMixin for DecimalArray
- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] passes `black pandas`
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

i guess should disable this for now
```
ERROR: /home/runner/work/pandas/pandas/pandas/_libs/tslibs/timezones.pxd Imports are incorrectly sorted and/or formatted.
ERROR: /home/runner/work/pandas/pandas/pandas/_libs/tslibs/offsets.pxd Imports are incorrectly sorted and/or formatted.
ERROR: /home/runner/work/pandas/pandas/pandas/_libs/tslibs/timestamps.pxd Imports are incorrectly sorted and/or formatted.
ERROR: /home/runner/work/pandas/pandas/pandas/_libs/tslibs/ccalendar.pxd Imports are incorrectly sorted and/or formatted.
ERROR: /home/runner/work/pandas/pandas/pandas/_libs/tslibs/conversion.pxd Imports are incorrectly sorted and/or formatted.
ERROR: /home/runner/work/pandas/pandas/pandas/_libs/tslibs/np_datetime.pxd Imports are incorrectly sorted and/or formatted.
ERROR: /home/runner/work/pandas/pandas/pandas/_libs/tslibs/timedeltas.pxd Imports are incorrectly sorted and/or formatted.
ERROR: /home/runner/work/pandas/pandas/pandas/_libs/tslibs/period.pxd Imports are incorrectly sorted and/or formatted.
Check import format using isort DONE
``` > i guess should disable this for now

I thought i saw a PR that addressed that.  if i dont find it ill open one shortly yah looks like someone already got to the isort thing, so this is green