chore: use ad-hoc signing on darwin to avoid network popups

[briandealwis]

Add a codesign step to sign the Skaffold binary with an ad-hoc signature. This seems to avoid the macOS prompts to accept incoming network connections.

[codecov]

Codecov Report

Merging #6738 (58f5547) into main (290280e) will decrease coverage by 0.82%.
The diff coverage is 57.14%.

@@            Coverage Diff             @@
##             main    #6738      +/-   ##
==========================================
- Coverage   70.48%   69.65%   -0.83%     
==========================================
  Files         515      527      +12     
  Lines       23150    24096     +946     
==========================================
+ Hits        16317    16784     +467     
- Misses       5776     6209     +433     
- Partials     1057     1103      +46     

Impacted Files	Coverage Δ
cmd/skaffold/app/cmd/flags.go	89.00% <0.00%> (-1.82%)	⬇️
cmd/skaffold/skaffold.go	0.00% <ø> (ø)
cmd/skaffold/app/cmd/cmd.go	70.32% <66.66%> (-0.73%)	⬇️
cmd/skaffold/app/cmd/debug.go	100.00% <100.00%> (ø)
cmd/skaffold/app/cmd/runner.go	64.17% <100.00%> (ø)
pkg/skaffold/initializer/build/builders.go	42.85% <0.00%> (-17.15%)	⬇️
pkg/skaffold/build/cluster/logs.go	0.00% <0.00%> (-16.67%)	⬇️
pkg/skaffold/event/v2/status_check.go	85.45% <0.00%> (-14.55%)	⬇️
pkg/skaffold/kubernetes/watcher.go	67.10% <0.00%> (-14.53%)	⬇️
.../skaffold/kubernetes/status/resource/deployment.go	72.41% <0.00%> (-13.39%)	⬇️
... and 93 more

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