style: apply black formatting across codebase 🎨

No logic changes — pure reformatting of line lengths, dict literals,
method-chain line breaks, and trailing newlines to satisfy black's style.

tests/test_zone_parser.py

@@ -1,4 +1,5 @@
 """Tests for directdnsonly.app.utils.zone_parser."""
+
 import pytest
 from dns.exception import DNSException