gh actions: use macos-15-intel for x86 tests (#112)

Author: hkratz

.github/workflows/ci.yml

@@ -16,18 +16,18 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-latest, macos-latest, windows-latest, macos-13]
+        os: [ubuntu-latest, macos-latest, windows-latest, macos-15-intel]
         toolchain: ["1.38.0", "1.61.0", stable, beta, nightly]
         exclude:
           - os: macos-latest
             toolchain: "1.38.0" # macOS ARM64 is not supported by 1.38.0
-          - os: macos-13
+          - os: macos-15-intel
             toolchain: "1.38.0" # macOS is not supported by 1.38.0 (flexpect)
           - toolchain: "1.61.0" # only macos
         include:
           - os: macos-latest
             toolchain: "1.61.0"
-          - os: macos-13
+          - os: macos-15-intel
             toolchain: "1.61.0"
     env:
       RUSTFLAGS: "-D warnings"