fix: get directories from dataset_builders/pie folder

.github/workflows/test_datasets_single.yaml

@@ -27,7 +27,7 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - id: set-dirs # Give it an id to handle to get step outputs in the outputs key above
-        run: echo "::set-output name=dir::$(ls -d dataset_builders/pie | jq -R -s -c 'split("\n")[:-1]')"
+        run: echo "::set-output name=dir::$(ls dataset_builders/pie | jq -R -s -c 'split("\n")[:-1]')"
         # Define step output named dir base on ls command transformed to JSON thanks to jq
 
   test_pie: