Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/rust.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@f43a0e5ff2bd294095638e18286ca9a3d1956744 # v3
+    - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3 # v6
     - name: Run Rustfmt
       run: cargo fmt -- --check
     - name: Build