fix: dispose window scheduler

[bednar]

Related #640

Proposed Changes

Dispose scheduler when disposing write_api.

Checklist

• [x] CHANGELOG.md updated
• [x] Rebased/mergeable
• [x] pytest tests completes successfully
• [x] Commit messages are conventional
• [x] Sign CLA (if not already signed)

[codecov-commenter]

Codecov Report

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

Comparison is base (293ed7f) 90.40% compared to head (46ec063) 90.42%.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #641 +/- ## ========================================== + Coverage 90.40% 90.42% +0.01% ========================================== Files 39 39 Lines 3503 3509 +6 ========================================== + Hits 3167 3173 +6 Misses 336 336 ```

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