Reduce overhead to compare dns records

[bdraco]

No description provided.

[codecov-commenter]

Codecov Report

Merging #997 (6957380) into master (93ddf7c) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #997   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           23        23           
  Lines         2502      2502           
  Branches       408       408           
=========================================
  Hits          2502      2502           

Impacted Files	Coverage Δ
zeroconf/_dns.py	100.00% <100.00%> (ø)

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