Bump actions/checkout from 4.3.1 to 6.0.2 (#4)

Author: dependabot[bot]

.github/workflows/shellcheck.yml

@@ -9,6 +9,6 @@ jobs:
   shellcheck:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
       - name: Run shellcheck
         run: shellcheck cc.sh