[BUILD] Upgrade torch-npu to 2.5.1 (#661)

### What this PR does / why we need it?
The torch-npu 2.5.1 are published:
https://pypi.org/project/torch-npu/2.5.1/
It's time to remove all torch-npu dev version from vllm-ascend code base

### Does this PR introduce _any_ user-facing change?
Yes, using torch-npu 2.5.1

### How was this patch tested?
- [ ] CI passed
- [ ] Manually test
- [ ] Grep all `dev2025`

---------

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

.github/workflows/mypy.yaml

@@ -38,7 +38,8 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.9", "3.10", "3.11", "3.12"]
+        # TODO(yikun): Add 3.12 back when torch-npu support 3.12
+        python-version: ["3.9", "3.10", "3.11"]
     steps:
     - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
     - name: Set up Python ${{ matrix.python-version }}
@@ -47,7 +48,7 @@ jobs:
         python-version: ${{ matrix.python-version }}
     - name: Install dependencies
       run: |
-        pip install -r requirements-dev.txt
+        pip install -r requirements-dev.txt --extra-index-url https://download.pytorch.org/whl/cpu
 
     - name: Checkout vllm-project/vllm repo
       uses: actions/checkout@v4