Make fixes for Windows / CI

[NickleDave]

• Fixes the Nox session 'dev' so it works on Windows
• Fix how we convert numpy integers to Python native integers for Segment instances, so that it doesn't fail on Windows, where the default numpy integer dtype is int32 not int64

[codecov-commenter]

Codecov Report

Patch coverage: 54.54% and project coverage change: -0.25 :warning:

Comparison is base (64fcd8d) 94.10% compared to head (b76482b) 93.85%.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #238 +/- ## ========================================== - Coverage 94.10% 93.85% -0.25% ========================================== Files 41 41 Lines 1510 1514 +4 ========================================== Hits 1421 1421 - Misses 89 93 +4 ``` | [Impacted Files](https://codecov.io/gh/vocalpy/crowsetta/pull/238?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | Coverage Δ | | |---|---|---| | [noxfile.py](https://codecov.io/gh/vocalpy/crowsetta/pull/238?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-bm94ZmlsZS5weQ==) | `0.00% <0.00%> (ø)` | | | [tests/test\_sequence.py](https://codecov.io/gh/vocalpy/crowsetta/pull/238?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-dGVzdHMvdGVzdF9zZXF1ZW5jZS5weQ==) | `100.00% <100.00%> (ø)` | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None)

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