build(deps): update dnspython requirement from ~=2.2.1 to ~=2.3.0

Updates the requirements on [dnspython](https://github.com/rthalley/dnspython) to permit the latest version.
- [Release notes](https://github.com/rthalley/dnspython/releases)
- [Changelog](https://github.com/rthalley/dnspython/blob/master/doc/whatsnew.rst)
- [Commits](rthalley/dnspython@v2.2.1...v2.3.0)

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

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

requirements.txt

@@ -1,3 +1,3 @@
 acme~=1.10.1
 validators~=0.20.0
-dnspython~=2.2.1
+dnspython~=2.3.0