ci: Use updated checkout action

Author: mefistotelis

.github/workflows/build.yaml

@@ -31,13 +31,13 @@ jobs:
 
       - name: Checkout code at latest head
         if: "${{ inputs.refToBuild == '' }}"
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0
 
       - name: Checkout code at requested ref
         if: "${{ inputs.refToBuild != '' }}"
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           ref: ${{ inputs.refToBuild }}
           fetch-depth: 0