Update dependency sphinx to <=8.1.2

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
sphinx (changelog)	<=8.1.1 -> <=8.1.2

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Release Notes

sphinx-doc/sphinx (sphinx)

### [`v8.1.2`](https://redirect.github.com/sphinx-doc/sphinx/blob/HEAD/CHANGES.rst#Release-812-in-development) [Compare Source](https://redirect.github.com/sphinx-doc/sphinx/compare/v8.1.1...v8.1.2) \============================== ## Bugs fixed - [#​13012](https://redirect.github.com/sphinx-doc/sphinx/issues/13012): Expose :exc:`sphinx.errors.ExtensionError` in `sphinx.util` for backwards compatibility. This will be removed in Sphinx 9, as exposing the exception in `sphinx.util` was never intentional. :exc:`!ExtensionError` has been part of `sphinx.errors` since Sphinx 0.9. Patch by Adam Turner.

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Configuration

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