Bump certbot from 4.1.1 to 4.2.0 in /src

Bumps [certbot](https://github.com/certbot/certbot) from 4.1.1 to 4.2.0.
- [Release notes](https://github.com/certbot/certbot/releases)
- [Commits](certbot/certbot@v4.1.1...v4.2.0)

---
updated-dependencies:
- dependency-name: certbot
  dependency-version: 4.2.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

src/requirements.txt

@@ -1 +1 @@
-certbot==4.1.1
+certbot==4.2.0