Bump sphinxcontrib-applehelp from 1.0.2 to 1.0.6 in /extra_requirements

Bumps [sphinxcontrib-applehelp](https://github.com/sphinx-doc/sphinxcontrib-applehelp) from 1.0.2 to 1.0.6.
- [Release notes](https://github.com/sphinx-doc/sphinxcontrib-applehelp/releases)
- [Changelog](https://github.com/sphinx-doc/sphinxcontrib-applehelp/blob/master/CHANGES)
- [Commits](sphinx-doc/sphinxcontrib-applehelp@1.0.2...1.0.6)

---
updated-dependencies:
- dependency-name: sphinxcontrib-applehelp
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

extra_requirements/requirements-docs.txt

@@ -10,7 +10,7 @@ recommonmark==0.7.1
 scipy==1.7.3
 sphinx_rtd_theme==1.0.0
 sphinx==4.4.0
-sphinxcontrib_applehelp==1.0.2
+sphinxcontrib_applehelp==1.0.6
 sphinxcontrib_devhelp==1.0.2
 sphinxcontrib_htmlhelp==2.0.1
 sphinxcontrib_jsmath==1.0.1