build(deps): update nbconvert requirement in /requirements

Updates the requirements on [nbconvert](https://github.com/jupyter/nbconvert) to permit the latest version.
- [Release notes](https://github.com/jupyter/nbconvert/releases)
- [Changelog](https://github.com/jupyter/nbconvert/blob/main/CHANGELOG.md)
- [Commits](jupyter/nbconvert@4.0.0...v7.16.6)

---
updated-dependencies:
- dependency-name: nbconvert
  dependency-version: 7.16.6
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements/docs.txt

@@ -1,7 +1,7 @@
 sphinx >5.0, <6.0
 myst-parser >=0.18.1, <3.0.0
 nbsphinx >=0.8.5, <=0.9.7
-nbconvert <7.14  # temporary fix for https://github.com/jupyter/nbconvert/issues/2092
+nbconvert <7.17  # temporary fix for https://github.com/jupyter/nbconvert/issues/2092
 pandoc >=1.0, <=2.3
 docutils >=0.16, <0.22
 sphinxcontrib-fulltoc >=1.0, <=1.2.0