Bump coverage from 7.6.4 to 7.6.8

Bumps [coverage](https://github.com/nedbat/coveragepy) from 7.6.4 to 7.6.8.
- [Release notes](https://github.com/nedbat/coveragepy/releases)
- [Changelog](https://github.com/nedbat/coveragepy/blob/master/CHANGES.rst)
- [Commits](nedbat/coveragepy@7.6.4...7.6.8)

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

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

pyproject.toml

@@ -47,7 +47,7 @@ docs = [
 tests = [
   "pytest==8.3.4",
   "pytest-cov==6.0.0",
-  "coverage==7.6.4",
+  "coverage==7.6.8",
   "werkzeug==3.1.1",
   "flask==3.1.0",
   "marshmallow==3.23.1",