Bump dnspython from 2.1.0 to 2.3.0

Bumps [dnspython](https://github.com/rthalley/dnspython) from 2.1.0 to 2.3.0.
- [Release notes](https://github.com/rthalley/dnspython/releases)
- [Changelog](https://github.com/rthalley/dnspython/blob/master/doc/whatsnew.rst)
- [Commits](https://github.com/rthalley/dnspython/compare/v2.1.0...v2.3.0)

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

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

requirements.txt

@@ -5,7 +5,7 @@ cffi==1.15.1
 chardet==3.0.4
 click==8.0.3
 cssselect==1.1.0
-dnspython==2.1.0
+dnspython==2.3.0
 docker==4.4.1
 feedparser==6.0.8
 gitdb==4.0.9