Use typing.Self

[radarhere]

Suggestion for python-pillow#9750, as per https://docs.python.org/3/whatsnew/3.11.html#whatsnew311-pep673

[codspeed]

Merging this PR will not alter performance

✅ 345 untouched benchmarks
⏩ 2 skipped benchmarks¹

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_{Comparing radarhere:rm-3.10 (2f15eb1) with rm-3.10 (09c72fa)}

Footnotes

1. 2 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. ↩

[hugovk]

Thanks!