[CI] Upgrade vLLM to 20250920 (c60e613) and address config break (#3067)

### What this PR does / why we need it?
Bump main to
c60e6137f0

- Updated imports in `vllm.config` to
`vllm.config.model`(aed16879a9)
https://github.com/vllm-project/vllm/pull/25252

- Refactored `vllm_ascend/sample/sampler.py` to use string values for
`logprobs_mode` instead of the `LogprobsMode` enum, simplifying logprobs
mode handling and improving compatibility with recent vLLM changes
(aed16879a9)
https://github.com/vllm-project/vllm/pull/25252

### Does this PR introduce _any_ user-facing change?
No

### How was this patch tested?
CI passed


- vLLM version: v0.10.2
- vLLM main:
6d8246aaff

---------

Signed-off-by: Yikun Jiang <yikunkero@gmail.com>

tests/e2e/conftest.py

@@ -32,7 +32,14 @@ from transformers import (AutoConfig, AutoModelForCausalLM, AutoTokenizer,
                           BatchEncoding, BatchFeature)
 from transformers.models.auto.auto_factory import _BaseAutoModelClass
 from vllm import LLM, SamplingParams
-from vllm.config import TaskOption, _get_and_verify_dtype
+
+from vllm_ascend.utils import vllm_version_is
+
+if vllm_version_is("0.10.2"):
+    from vllm.config import TaskOption, _get_and_verify_dtype
+else:
+    from vllm.config.model import TaskOption, _get_and_verify_dtype
+
 from vllm.inputs import TextPrompt
 from vllm.outputs import RequestOutput
 from vllm.transformers_utils.utils import maybe_model_redirect