add check for if there are samples to be checked under validate samples job.

Signed-off-by: Michael Valdron <mvaldron@redhat.com>

Author: michael-valdron

.github/workflows/validate-samples.yaml

@@ -58,4 +58,5 @@ jobs:
         run: echo "STACKS=$(bash tests/build_parents_file.sh)" >> $GITHUB_ENV
 
       - name: Validate samples
+        if: ${{ env.STACKS != '' }}
         run: STACKS_DIR=$(pwd)/samples/.cache bash tests/validate_devfile_schemas.sh