Bump nbconvert from 7.4.0 to 7.6.0 (#311)

Bumps [nbconvert](https://github.com/jupyter/nbconvert) from 7.4.0 to 7.6.0.
- [Release notes](https://github.com/jupyter/nbconvert/releases)
- [Changelog](https://github.com/jupyter/nbconvert/blob/main/CHANGELOG.md)
- [Commits](jupyter/nbconvert@v7.4.0...v7.6.0)

---
updated-dependencies:
- dependency-name: nbconvert
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements_dev.txt

@@ -15,5 +15,5 @@ coverage[toml]>=4.5.4
 -r docs/requirements.txt
 # package runtime requirements
 flake8==5.0.4
-nbconvert==7.4.0; python_version > '3.7'
+nbconvert==7.6.0; python_version > '3.7'
 ipython==8.14.0; python_version >= '3.9'