Update key4hep-build.yaml

Author: jmcarcell

.github/workflows/key4hep-build.yaml

@@ -22,15 +22,13 @@ jobs:
       matrix:
         build_type: ["release", "nightly"]
         image: ["alma9"]
-        stack: ["key4hep"]
         include:
           - build_type: nightly
             image: ubuntu24
-            stack: key4hep
       fail-fast: false
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
     - uses: key4hep/key4hep-actions/cache-external-data@main
     - uses: key4hep/key4hep-actions/key4hep-build@main
       with: