Remove darwin-amd64 builds since it is no longer supported

* See truffleruby/truffleruby#4011

Author: eregon

.github/workflows/build.yml

@@ -78,7 +78,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ ubuntu-22.04, ubuntu-24.04, ubuntu-22.04-arm, ubuntu-24.04-arm, macos-15-intel, macos-14 ]
+        os: [ ubuntu-22.04, ubuntu-24.04, ubuntu-22.04-arm, ubuntu-24.04-arm, macos-14 ]
         name: [ '-head', '+graalvm-head' ]
     runs-on: ${{ matrix.os }}
     steps:
@@ -92,7 +92,6 @@ jobs:
       id: platform
       run: |
         platform=${{ matrix.os }}
-        platform=${platform/macos-15-intel/darwin-x64}
         platform=${platform/macos-14/darwin-arm64}
         platform=${platform/%.04/.04-x64}
         platform=${platform/%.04-arm/.04-arm64}