ci: Expand stack test matrix

Author: liskin

Diff for: .github/workflows/stack.yml

@@ -25,8 +25,10 @@ jobs:
           - resolver: lts-20  # GHC 9.2
             yaml: stack-master.yaml
           - resolver: lts-21  # GHC 9.4
+            yaml: stack-master.yaml
+          - resolver: lts-22  # GHC 9.6
             yaml: stack.yaml
-          - resolver: lts-21  # GHC 9.4
+          - resolver: lts-22  # GHC 9.6
             yaml: stack-master.yaml
 
     steps: