feat: use server_key when processing DNSService records

[bdraco]

This is a small cleanup to avoid calling .lower() when we already have the server_key. performance benefit is negligible

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: -0.04% ⚠️

Comparison is base (68d9998) 99.82% compared to head (7879823) 99.78%.
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1238      +/-   ##
==========================================
- Coverage   99.82%   99.78%   -0.04%     
==========================================
  Files          25       25              
  Lines        2805     2805              
  Branches      479      479              
==========================================
- Hits         2800     2799       -1     
  Misses          3        3              
- Partials        2        3       +1     

Files Changed	Coverage Δ
src/zeroconf/__init__.py	100.00% <100.00%> (ø)
src/zeroconf/_core.py	100.00% <100.00%> (ø)
src/zeroconf/_services/info.py	100.00% <100.00%> (ø)

... and 1 file with indirect coverage changes

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.