build(deps): bump pytest from 8.4.2 to 9.0.0 in /book/src

Bumps [pytest](https://github.com/pytest-dev/pytest) from 8.4.2 to 9.0.0.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/main/CHANGELOG.rst)
- [Commits](pytest-dev/pytest@8.4.2...9.0.0)

---
updated-dependencies:
- dependency-name: pytest
  dependency-version: 9.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

book/src/requirements.txt

@@ -10,7 +10,7 @@ pinject==0.14.1
 pip-tools==7.5.1
 pyflakes==3.2.0
 pylint==3.3.9
-pytest==8.4.2
+pytest==9.0.0
 pytest-cov==5.0.0
 pytype==2024.9.13
 requests==2.32.5