feat: add workflow parallel depth limit configuration (#11460)

Signed-off-by: -LAN- <laipz8200@outlook.com>
Co-authored-by: zxhlyh <jasonapring2015@outlook.com>

api/tests/unit_tests/configs/test_dify_config.py

@@ -59,6 +59,8 @@ def test_dify_config(example_env_file):
     # annotated field with configured value
     assert config.HTTP_REQUEST_MAX_WRITE_TIMEOUT == 30
 
+    assert config.WORKFLOW_PARALLEL_DEPTH_LIMIT == 3
+
 
 # NOTE: If there is a `.env` file in your Workspace, this test might not succeed as expected.
 # This is due to `pymilvus` loading all the variables from the `.env` file into `os.environ`.