Bump certifi from 2026.4.22 to 2026.5.20

Bumps [certifi](https://github.com/certifi/python-certifi) from 2026.4.22 to 2026.5.20.
- [Commits](certifi/python-certifi@2026.04.22...2026.05.20)

---
updated-dependencies:
- dependency-name: certifi
  dependency-version: 2026.5.20
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

requirements-dev.txt

@@ -1,7 +1,7 @@
 -r requirements.txt
 attrs==26.1.0
 build==1.4.4
-certifi==2026.4.22
+certifi==2026.5.20
 colorama==0.4.6
 flake8==7.3.0
 iniconfig==2.1.0