[CI] Test Krylov.jl on Mac x86_64 (#1032)

* [CI] Test Krylov.jl on Mac x86_64

* Update .github/workflows/ci.yml

Author: amontoison

.github/workflows/ci.yml

@@ -14,7 +14,7 @@ jobs:
       fail-fast: false
       matrix:
         version: ['lts', '1']
-        os: [ubuntu-latest, macos-latest, windows-latest]
+        os: [ubuntu-latest, macos-latest, windows-latest, macos-15-intel]
         arch: [x64]
         allow_failure: [false]
         include: