Drop vLLM 0.13.0 support (#6069)

### What this PR does / why we need it?
Drop vLLM 0.13.0 support, upgrade to 0.14.0

- vLLM version: v0.13.0
- vLLM main:
d68209402d

---------

Signed-off-by: hfadzxy <starmoon_zhang@163.com>

vllm_ascend/attention/mla_v1.py

@@ -10,7 +10,10 @@ from vllm.forward_context import ForwardContext, get_forward_context
 from vllm.logger import logger
 from vllm.model_executor.layers.linear import UnquantizedLinearMethod
 from vllm.utils.math_utils import cdiv, round_down
+from vllm.v1.attention.backend import (  # type: ignore
+    AttentionBackend, AttentionCGSupport, MLAAttentionImpl)
 from vllm.v1.attention.backends.mla.common import MLACommonMetadataBuilder
+from vllm.v1.attention.backends.utils import PAD_SLOT_ID  # type: ignore
 from vllm.v1.kv_cache_interface import AttentionSpec, MLAAttentionSpec
 
 from vllm_ascend import envs
@@ -35,23 +38,12 @@ from vllm_ascend.ops.rotary_embedding import get_cos_and_sin_mla
 from vllm_ascend.ops.weight_prefetch import maybe_npu_prefetch
 from vllm_ascend.quantization.w8a8 import AscendW8A8LinearMethod
 from vllm_ascend.utils import (ACL_FORMAT_FRACTAL_ND, maybe_trans_nz,
-                               vllm_version_is, weak_ref_tensors)
+                               weak_ref_tensors)
 from vllm_ascend.worker.npu_input_batch import NPUInputBatch
 
 if TYPE_CHECKING:
     from vllm.v1.core.sched.output import SchedulerOutput
 
-# isort: off
-if vllm_version_is('0.13.0'):
-    from vllm.v1.attention.backends.utils import AttentionCGSupport
-    from vllm.attention.backends.abstract import (  # type: ignore
-        AttentionBackend, MLAAttentionImpl)
-    from vllm.attention.backends.utils import PAD_SLOT_ID  # type: ignore
-else:
-    from vllm.v1.attention.backend import (  # type: ignore
-        AttentionBackend, AttentionCGSupport, MLAAttentionImpl)
-    from vllm.v1.attention.backends.utils import PAD_SLOT_ID  # type: ignore
-# isort: on
 
 MAX_O_PROJ_PREFETCH_SIZE = 16 * 1024 * 1024
 BUILD_METADATA_STEP_PREFILL = 0