build(deps): bump importlib-metadata in /docker/test-shadow

Bumps [importlib-metadata](https://github.com/python/importlib_metadata) from 5.0.0 to 6.0.0.
- [Release notes](https://github.com/python/importlib_metadata/releases)
- [Changelog](https://github.com/python/importlib_metadata/blob/main/CHANGES.rst)
- [Commits](python/importlib_metadata@v5.0.0...v6.0.0)

---
updated-dependencies:
- dependency-name: importlib-metadata
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

docker/test-shadow/requirements.txt

@@ -1,6 +1,6 @@
 click==8.1.3              # via flask
 flask==2.2.2
-importlib-metadata==5.0.0 # via click
+importlib-metadata==6.0.0 # via click
 itsdangerous==2.1.2       # via flask
 jinja2==3.1.2             # via flask
 markupsafe==2.1.1         # via jinja2