CI/Tests failing

[gordonwatts]

They just started failing quietly a few months ago. This PR will get everything working again.

• Fixed issues where black had reformatted code so that we couldn't tell where one method started and the other ended.
• Modern version of flake8 is catching more errors now.
• The python 3.7 on macOS failure may have been suprious - it seems to work currently on the CI infrastructure.

Fixes #214

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (a284336) 95.15% compared to head (242e8f0) 95.05%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #215 +/- ## ========================================== - Coverage 95.15% 95.05% -0.11% ========================================== Files 35 35 Lines 1880 1880 Branches 249 249 ========================================== - Hits 1789 1787 -2 - Misses 59 60 +1 - Partials 32 33 +1 ``` | [Flag](https://app.codecov.io/gh/iris-hep/func_adl_xAOD/pull/215/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=iris-hep) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/iris-hep/func_adl_xAOD/pull/215/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=iris-hep) | `95.05% <100.00%> (-0.11%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=iris-hep#carryforward-flags-in-the-pull-request-comment) to find out more. | [Files](https://app.codecov.io/gh/iris-hep/func_adl_xAOD/pull/215?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=iris-hep) | Coverage Δ | | |---|---|---| | [func\_adl\_xAOD/common/ast\_to\_cpp\_translator.py](https://app.codecov.io/gh/iris-hep/func_adl_xAOD/pull/215?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=iris-hep#diff-ZnVuY19hZGxfeEFPRC9jb21tb24vYXN0X3RvX2NwcF90cmFuc2xhdG9yLnB5) | `88.04% <100.00%> (-0.42%)` | :arrow_down: |

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