Bump importlib-metadata from 4.6.0 to 4.6.3 in /extra_requirements (#610

)

Bumps [importlib-metadata](https://github.com/python/importlib_metadata) from 4.6.0 to 4.6.3.
- [Release notes](https://github.com/python/importlib_metadata/releases)
- [Changelog](https://github.com/python/importlib_metadata/blob/main/CHANGES.rst)
- [Commits](python/importlib_metadata@v4.6.0...v4.6.3)

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

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Joran Angevaare <jorana@nikhef.nl>

extra_requirements/requirements-tests.txt

@@ -12,7 +12,7 @@ commentjson==0.9.0
 coverage==5.5
 flake8==3.9.2
 holoviews==1.14.5
-importlib-metadata==4.6.0; python_version=="3.7"
+importlib-metadata==4.6.3; python_version=="3.7"
 ipywidgets==7.6.3
 hypothesis==6.14.5
 jupyter-client==6.1.12                          # for ipywidgets