tweak ci to skip external graph drivers

Author: Luca Candela

.github/workflows/ci.yml

@@ -35,6 +35,11 @@ jobs:
         run: uv sync --extra dev
 
       - name: Run targeted tests
+        env:
+          DISABLE_NEO4J: '1'
+          DISABLE_FALKORDB: '1'
+          DISABLE_KUZU: '1'
+          DISABLE_NEPTUNE: '1'
         run: |
           uv run pytest tests/orchestration/test_bulk_serialization.py tests/search/test_search_utils_filters.py
           uv run pytest tests/test_graphium_mock.py::test_add_episode_persists_nodes_and_edges