feat: speed up parsing NSEC records

[bdraco]

Benchmark before
Parsing 100000 incoming messages took 3.846316208015196 seconds

Benchmark after
Parsing 100000 incoming messages took 2.7343544159957673 seconds

Almost a 39% improvement

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (fbaaf7b) 99.81% compared to head (5f8404e) 99.81%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1169   +/-   ##
=======================================
  Coverage   99.81%   99.81%           
=======================================
  Files          22       22           
  Lines        2667     2671    +4     
  Branches      464      464           
=======================================
+ Hits         2662     2666    +4     
  Misses          3        3           
  Partials        2        2           

Impacted Files	Coverage Δ
src/zeroconf/__init__.py	100.00% <100.00%> (ø)
src/zeroconf/_protocol/incoming.py	98.96% <100.00%> (+0.02%)	⬆️

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