runner -> matrix

Author: nitinprakash96

.github/workflows/haskell-ci.yml

@@ -51,7 +51,7 @@ jobs:
         run: cabal test --enable-tests
 
   stack:
-    name: ${{ runner.os }} / ${{ matrix.stack-yaml }}
+    name: ${{ matrix.os }} / ${{ matrix.stack-yaml }}
     runs-on: ${{ matrix.os }}
     strategy:
       matrix: