Bump actions/checkout from 4 to 6 (#5015)

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 6.

- vLLM version: v0.12.0
- vLLM main:
ad32e3e19c

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/_e2e_test.yaml

@@ -41,7 +41,7 @@ jobs:
           apt install git -y
 
       - name: Checkout vllm-project/vllm-ascend repo
-        uses: actions/checkout@v6.0.1
+        uses: actions/checkout@v6
 
       - name: Install system dependencies
         run: |
@@ -49,7 +49,7 @@ jobs:
           apt-get -y install gcc g++ cmake libnuma-dev
 
       - name: Checkout vllm-project/vllm repo
-        uses: actions/checkout@v6.0.1
+        uses: actions/checkout@v6
         with:
           repository: vllm-project/vllm
           ref: ${{ inputs.vllm }}
@@ -137,7 +137,7 @@ jobs:
           apt install git -y
 
       - name: Checkout vllm-project/vllm-ascend repo
-        uses: actions/checkout@v6.0.1
+        uses: actions/checkout@v6
 
       - name: Install system dependencies
         run: |
@@ -145,7 +145,7 @@ jobs:
           apt-get -y install gcc g++ cmake libnuma-dev
 
       - name: Checkout vllm-project/vllm repo
-        uses: actions/checkout@v6.0.1
+        uses: actions/checkout@v6
         with:
           repository: vllm-project/vllm
           ref: ${{ inputs.vllm }}
@@ -229,7 +229,7 @@ jobs:
           git config --global url."https://gh-proxy.test.osinfra.cn/https://github.com/".insteadOf https://github.com/
 
       - name: Checkout vllm-project/vllm-ascend repo
-        uses: actions/checkout@v6.0.1
+        uses: actions/checkout@v6
         with:
           path: ./vllm-ascend
 
@@ -239,7 +239,7 @@ jobs:
           apt-get -y install gcc g++ cmake libnuma-dev
 
       - name: Checkout vllm-project/vllm repo
-        uses: actions/checkout@v6.0.1
+        uses: actions/checkout@v6
         with:
           repository: vllm-project/vllm
           ref: ${{ inputs.vllm }}