ci: remove libz-dev from macOS build deps

Remove no-longer used libz-dev (from DMG compression).
Followup to #28432.
Missed this in #28932.

ci/test/00_setup_env_mac.sh

@@ -11,7 +11,7 @@ export SDK_URL=${SDK_URL:-https://bitcoincore.org/depends-sources/sdks}
 export CONTAINER_NAME=ci_macos_cross
 export CI_IMAGE_NAME_TAG="docker.io/ubuntu:22.04"
 export HOST=x86_64-apple-darwin
-export PACKAGES="cmake libz-dev zip"
+export PACKAGES="cmake zip"
 export XCODE_VERSION=12.2
 export XCODE_BUILD_ID=12B45b
 export RUN_UNIT_TESTS=false