Updating github-config

Author: cf-buildpacks-eng

.github/workflows/test-pull-request.yml

@@ -31,12 +31,15 @@ jobs:
       matrix: ${{ steps.set-matrix.outputs.matrix }}
     needs: unit
     steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
       - name: Set Matrix
         id: set-matrix
         run: |
           matrix="$(jq -r -c '.integration.matrix' ./config.json)"
           printf "Output: matrix=%s\n" "${matrix}"
-          printf "matrix=%s\n" "${matrix}"
+          printf "matrix=%s\n" "${matrix}" >> "$GITHUB_OUTPUT"
 
   integration:
     name: Integration Test