build(deps): bump coverage from 7.6.8 to 7.6.9 in /book/src

Bumps [coverage](https://github.com/nedbat/coveragepy) from 7.6.8 to 7.6.9.
- [Release notes](https://github.com/nedbat/coveragepy/releases)
- [Changelog](https://github.com/nedbat/coveragepy/blob/master/CHANGES.rst)
- [Commits](coveragepy/coveragepy@7.6.8...7.6.9)

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

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

Author: dependabot[bot]

book/src/requirements.txt

@@ -1,5 +1,5 @@
 black==24.10.0
-coverage==7.6.8
+coverage==7.6.9
 flake8==7.1.1
 hypothesis==6.122.1
 isort==5.13.2