ci: drop macOS x86_64 build — Rosetta runs arm64 binary

macos-13 is retired and macos-15-large requires a paid plan.
Intel Macs can run the arm64 binary via Rosetta 2.

Author: dvershinin

.github/workflows/frozen-binaries.yml

@@ -17,10 +17,6 @@ jobs:
             os: darwin
             arch: arm64
             artifact: gixy-darwin-arm64
-          - runner: macos-15-large
-            os: darwin
-            arch: x86_64
-            artifact: gixy-darwin-x86_64
           - runner: ubuntu-latest
             os: linux
             arch: x86_64