Bump dnspython from 2.6.1 to 2.8.0 in /docker

Bumps [dnspython](https://github.com/rthalley/dnspython) from 2.6.1 to 2.8.0.
- [Release notes](https://github.com/rthalley/dnspython/releases)
- [Changelog](https://github.com/rthalley/dnspython/blob/main/doc/whatsnew.rst)
- [Commits](rthalley/dnspython@v2.6.1...v2.8.0)

---
updated-dependencies:
- dependency-name: dnspython
  dependency-version: 2.8.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

docker/requirements.txt

@@ -5,5 +5,5 @@ psycopg2-binary==2.9.10
 python-dateutil==2.9.0.post0
 Pillow==12.2.0
 requests==2.33.0
-dnspython==2.6.1
+dnspython==2.8.0
 gunicorn==23.0.0