ci: build the intel mac program on apple silicon

Author: maxmalkin

.github/workflows/release.yml

@@ -18,10 +18,14 @@ jobs:
         include:
           - os: macos-14
             target: aarch64-apple-darwin
-          - os: macos-13
+          # Apple Silicon runners can build the Intel program. Intel
+          # runners are scarce, thus this is quicker.
+          - os: macos-14
             target: x86_64-apple-darwin
           - os: ubuntu-latest
             target: x86_64-unknown-linux-gnu
+          - os: ubuntu-24.04-arm
+            target: aarch64-unknown-linux-gnu
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v4