Bump certifi from 2026.1.4 to 2026.2.25 in /demos

Bumps [certifi](https://github.com/certifi/python-certifi) from 2026.1.4 to 2026.2.25.
- [Commits](certifi/python-certifi@2026.01.04...2026.02.25)

---
updated-dependencies:
- dependency-name: certifi
  dependency-version: 2026.2.25
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

demos/moderator_bot/requirements-dev.txt

@@ -3,7 +3,7 @@ aiohttp==3.13.3
 async-timeout==5.0.1
 atomicwrites==1.4.1
 attrs==25.4.0
-certifi==2026.1.4
+certifi==2026.2.25
 chardet==5.2.0
 idna==3.11
 importlib-metadata==0.23 ; python_version < '3.8'