Fix ty 0.0.85 diagnostics in vortex-python

[connortsui20]

Summary

Python (lint) runs uvx ty check without a version pin, so ty 0.0.85 now fails it on develop and every open PR, including #10340.

Changes

Annotates the @contextmanager in dataset.py as Generator[None] instead of Iterator[None] and drops a redundant cast in test_expr.py. Both changes are annotation-only and also pass ty 0.0.84.

[connortsui20]

#10352

[codspeed]

Merging this PR will improve performance by 19.86%

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

⚡ 1 improved benchmark
✅ 2108 untouched benchmarks
🆕 2 new benchmarks
⏩ 518 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	WallTime	bitpack_blocked_compress_avx512	5.6 µs	4.7 µs	+19.86%
🆕	Simulation	integer_stats_all_non_null	N/A	1.2 ms	N/A
🆕	Simulation	integer_stats_all_nullable	N/A	3.6 ms	N/A

Tip

Curious why performance improved? Comment @codspeedbot explain why performance improved on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing ct/ty-0.0.85-diagnostics (7326b0b) with develop (d9ad4cf)²}

Footnotes

1. 518 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

2. No successful run was found on develop (9eb20ba) during the generation of this report, so d9ad4cf was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩