Merge pull request #564 from IntersectMBO/newhoggy/limit-macOS-jobs

CI: Limit to a single Haskell job on macOS

.github/workflows/haskell.yml

@@ -11,12 +11,16 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ghc: ["8.10.7", "9.2.7", "9.6.2"]
-        cabal: ["3.10.1.0"]
-        os: [ubuntu-latest, macos-latest, windows-latest]
-        exclude:
-          - ghc: "9.2.7"
-            os: macos-latest
+        # If you edit these versions, make sure the version in the lonely macos-latest job below is updated accordingly
+        ghc: ["9.2.8", "9.6.3"]
+        cabal: ["3.10.2.1"]
+        os: [windows-latest, ubuntu-latest]
+        include:
+          # Using include, to make sure there will only be one macOS job, even if the matrix gets expanded later on.
+          # We want a single job, because macOS runners are scarce.
+          - os: macos-latest
+            cabal: "3.10.2.1"
+            ghc: "9.6.3"
 
     env:
       # Modify this value to "invalidate" the cabal cache.