fix: update checkout action to v5 for consistency with other workflows

Author: cursoragent

.github/workflows/pr-tests-arm64.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-24.04
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
 
       - name: Setup Go
         uses: ./.github/actions/go-setup-cache
@@ -67,7 +67,7 @@ jobs:
       fail-fast: false
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
 
       - name: Setup Go
         uses: ./.github/actions/go-setup-cache