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

Author: renovate[bot]

.github/workflows/rust.yml

@@ -9,7 +9,7 @@ jobs:
 
     steps:
 
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: rustfmt
         run: .ci-scripts/rustfmt-check