build(deps): bump zensical in /docs in the patches group

Bumps the patches group in /docs with 1 update: [zensical](https://github.com/zensical/zensical).


Updates `zensical` from 0.0.27 to 0.0.28
- [Release notes](https://github.com/zensical/zensical/releases)
- [Commits](https://github.com/zensical/zensical/compare/v0.0.27...v0.0.28)

---
updated-dependencies:
- dependency-name: zensical
  dependency-version: 0.0.28
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: patches
...

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

docs/requirements.txt

@@ -22,4 +22,4 @@ PyYAML==6.0.3
 pyyaml_env_tag==1.1
 six==1.17.0
 watchdog==6.0.0
-zensical==0.0.27
+zensical==0.0.28