Fix matrix key in tests workflow

Author: iabudiab

.github/workflows/test.yml

@@ -13,7 +13,7 @@ jobs:
     continue-on-error: true
     strategy:
       matrix:
-        image: ["5.10", "6.0", "6.1"]
+        swift: ["5.10", "6.0", "6.1"]
     steps:
     - name: Checkout
       uses: actions/checkout@v5