chore(deps): Update dependency alabaster to v0.7.15

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
alabaster (source, changelog)	==0.7.13 -> ==0.7.15

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Release Notes

sphinx-doc/alabaster (alabaster)

### [`v0.7.15`](https://togithub.com/sphinx-doc/alabaster/releases/tag/0.7.15): Alabaster 0.7.15 [Compare Source](https://togithub.com/sphinx-doc/alabaster/compare/0.7.14...0.7.15) Changelog: https://alabaster.readthedocs.io/en/latest/changelog.html ### [`v0.7.14`](https://togithub.com/sphinx-doc/alabaster/releases/tag/0.7.14): Alabaster 0.7.14 [Compare Source](https://togithub.com/sphinx-doc/alabaster/compare/0.7.13...0.7.14) Changelog: https://alabaster.readthedocs.io/en/latest/changelog.html

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Configuration

📅 Schedule: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 Automerge: Enabled.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

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