chore(deps): update dependency sphinx-rtd-theme to v3.1.0 (#919)

This PR contains the following updates:

| Package | Change |
[Age](https://docs.renovatebot.com/merge-confidence/) |
[Confidence](https://docs.renovatebot.com/merge-confidence/) |
|---|---|---|---|
|
[sphinx-rtd-theme](https://redirect.github.com/readthedocs/sphinx_rtd_theme)
| `==3.0.2` → `==3.1.0` |
![age](https://developer.mend.io/api/mc/badges/age/pypi/sphinx-rtd-theme/3.1.0?slim=true)
|
![confidence](https://developer.mend.io/api/mc/badges/confidence/pypi/sphinx-rtd-theme/3.0.2/3.1.0?slim=true)
|
|
[sphinx-rtd-theme](https://redirect.github.com/readthedocs/sphinx_rtd_theme)
| `==3.1.0rc2` → `==3.1.0` |
![age](https://developer.mend.io/api/mc/badges/age/pypi/sphinx-rtd-theme/3.1.0?slim=true)
|
![confidence](https://developer.mend.io/api/mc/badges/confidence/pypi/sphinx-rtd-theme/3.1.0rc2/3.1.0?slim=true)
|

---

### Release Notes

<details>
<summary>readthedocs/sphinx_rtd_theme (sphinx-rtd-theme)</summary>

###
[`v3.1.0`](https://redirect.github.com/readthedocs/sphinx_rtd_theme/compare/3.0.2...3.1.0)

[Compare
Source](https://redirect.github.com/readthedocs/sphinx_rtd_theme/compare/3.0.2...3.1.0)

</details>

---

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requirements-dev.txt

@@ -5,8 +5,8 @@ tox==4.34.1 ; python_version < "3.10"
 wheel==0.46.1
 Sphinx==9.0.4 ; python_version >= "3.11"
 Sphinx==7.4.7 ; python_version < "3.11"
-sphinx-rtd-theme==3.1.0rc2 ; python_version >= "3.11"
-sphinx-rtd-theme==3.0.2 ; python_version < "3.11"
+sphinx-rtd-theme==3.1.0 ; python_version >= "3.11"
+sphinx-rtd-theme==3.1.0 ; python_version < "3.11"
 pypandoc==1.16.2
 twine==6.2.0
 black==25.12.0