Bump certifi from 2019.3.9 to 2022.12.7 in /docs

Bumps [certifi](https://github.com/certifi/python-certifi) from 2019.3.9 to 2022.12.7.
- [Release notes](https://github.com/certifi/python-certifi/releases)
- [Commits](certifi/python-certifi@2019.03.09...2022.12.07)

---
updated-dependencies:
- dependency-name: certifi
  dependency-type: direct:production
...

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

docs/requirements.txt

@@ -7,7 +7,7 @@
 alabaster==0.7.12
 Babel==2.9.1
 breathe==4.13.0.post0
-certifi==2019.3.9
+certifi==2022.12.7
 chardet==3.0.4
 docutils==0.14
 idna==2.8