Bump certifi from 2021.10.8 to 2022.12.7 in /doc/source

Bumps [certifi](https://github.com/certifi/python-certifi) from 2021.10.8 to 2022.12.7.
- [Release notes](https://github.com/certifi/python-certifi/releases)
- [Commits](certifi/python-certifi@2021.10.08...2022.12.07)

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

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

doc/source/requirements.txt

@@ -1,7 +1,7 @@
 alabaster==0.7.12
 Babel==2.9.1
 breathe==4.33.1
-certifi==2021.10.8
+certifi==2022.12.7
 charset-normalizer==2.0.12
 colorama==0.4.4
 docutils==0.17.1