chore(deps): update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/deadlock_tool.yml

@@ -7,7 +7,7 @@ jobs:
   build:
     runs-on: windows-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v6
     - uses: actions/setup-go@v2
       with:
         go-version: '1.25.4'