Bump actions/checkout from 3 to 6 (#742)

Author: tanya732

.github/workflows/semgrep.yml

@@ -17,7 +17,7 @@ jobs:
       image: returntocorp/semgrep
     if: (github.actor != 'dependabot[bot]')
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v6
 
       - run: semgrep ci
         env: