pip: bump sphinxcontrib-htmlhelp from 2.0.3 to 2.0.4

Bumps [sphinxcontrib-htmlhelp](https://github.com/sphinx-doc/sphinxcontrib-htmlhelp) from 2.0.3 to 2.0.4.
- [Release notes](https://github.com/sphinx-doc/sphinxcontrib-htmlhelp/releases)
- [Changelog](https://github.com/sphinx-doc/sphinxcontrib-htmlhelp/blob/2.0.4/CHANGES)
- [Commits](sphinx-doc/sphinxcontrib-htmlhelp@2.0.3...2.0.4)

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

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

requirements.txt

@@ -22,7 +22,7 @@ sphinx-intl==2.1.0
 sphinx-lint==0.6.8
 sphinxcontrib-applehelp==1.0.4
 sphinxcontrib-devhelp==1.0.4
-sphinxcontrib-htmlhelp==2.0.3
+sphinxcontrib-htmlhelp==2.0.4
 sphinxcontrib-jsmath==1.0.1
 sphinxcontrib-qthelp==1.0.3
 sphinxcontrib-serializinghtml==1.1.9