update actions version (#372)

Signed-off-by: YanxuanLiu <[email protected]>

Author: YanxuanLiu

.github/workflows/auto-merge.yml

@@ -27,7 +27,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           ref: branch-24.04 # force to fetch from latest upstream instead of PR ref
 

.github/workflows/signoff-check.yml

@@ -23,7 +23,7 @@ jobs:
   signoff-check:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
 
       - name: sigoff-check job
         uses: ./.github/workflows/signoff-check