dns/py-pydnstable: Upgrade to version 0.7.3

pydnstable (0.7.3-1) debian-farsightsec; urgency=medium

• Fix bug in Python3 support.
• Add simple tests for text and fmt_dict output

MFH: 2022Q2
Sponsored by: DomainTools

(cherry picked from commit 051701ce15a83ddf612020a92af2010a79073e3e)