Remove 3.7

[codecov[bot]]

Codecov Report

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

Comparison is base (37c7117) 97.72% compared to head (ee7ac2a) 97.61%. Report is 2 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #193 +/- ## ========================================== - Coverage 97.72% 97.61% -0.12% ========================================== Files 17 17 Lines 1758 1758 ========================================== - Hits 1718 1716 -2 - Misses 40 42 +2 ``` | [Flag](https://app.codecov.io/gh/dandi/dandi-schema/pull/193/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dandi) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/dandi/dandi-schema/pull/193/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dandi) | `97.61% <ø> (-0.12%)` | :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=dandi#carryforward-flags-in-the-pull-request-comment) to find out more. [see 2 files with indirect coverage changes](https://app.codecov.io/gh/dandi/dandi-schema/pull/193/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dandi)

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[yarikoptic]

type checking is clearly unrelated but we do have more of 3.7 to upgrade...

[yarikoptic]

linters -- codespell

lint: commands[0]> codespell dandischema setup.py
dandischema/tests/data/metadata/meta_000004.json:6: re-use ==> reuse
dandischema/tests/data/metadata/meta_000004old.json:413: re-use ==> reuse

I will push to this PR just because so small

[yarikoptic]

whatever test fails to happen -- should be fixed ,but not related, thus continueing