[Bugfix]Lazy import vllm config (#462)

### What this PR does / why we need it?
Lazy import vllm config  to avoid circular imports

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Signed-off-by: wangli <wangli858794774@gmail.com>

pytest.ini

@@ -43,6 +43,7 @@ norecursedirs =
 addopts = --ignore=vllm-empty/tests/test_utils.py
           --ignore=vllm-empty/tests/test_config.py
           --ignore=vllm-empty/tests/test_scalartype.py
+          --ignore=vllm-empty/tests/test_version.py
           --ignore=vllm-empty/tests/test_embedded_commit.py
           --ignore=vllm-empty/tests/test_inputs.py
           --ignore=vllm-empty/tests/test_sharded_state_loader.py