[CI] Add git safe repo (#7501)

### What this PR does / why we need it?
Add git safe repo to avoid dubious ownership error

- vLLM version: v0.17.0
- vLLM main:
8b6325758c
---------
Signed-off-by: wangli <wangli858794774@gmail.com>

.github/workflows/_unit_test.yaml

@@ -42,6 +42,7 @@ jobs:
           pip config set global.trusted-host cache-service.nginx-pypi-cache.svc.cluster.local
           apt-get update -y
           apt-get install -y python3-pip git vim wget net-tools gcc g++ cmake libnuma-dev curl gnupg2
+          git config --global --add safe.directory /__w/vllm-ascend/vllm-ascend
           pip install uv
 
       - name: Checkout vllm-project/vllm repo