build(deps): bump pytest from 8.3.3 to 8.3.4 in /lib/spack/docs (#47882)

Bumps [pytest](https://github.com/pytest-dev/pytest) from 8.3.3 to 8.3.4.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/main/CHANGELOG.rst)
- [Commits](https://github.com/pytest-dev/pytest/compare/8.3.3...8.3.4)

---
updated-dependencies:
- dependency-name: pytest
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

lib/spack/docs/requirements.txt

@@ -6,7 +6,7 @@ python-levenshtein==0.26.1
 docutils==0.21.2
 pygments==2.18.0
 urllib3==2.2.3
-pytest==8.3.3
+pytest==8.3.4
 isort==5.13.2
 black==24.10.0
 flake8==7.1.1