only add for cargo.lock

.github/workflows/dependabot-pr.yml

@@ -39,6 +39,6 @@ jobs:
         run: |
           git config user.email "49699333+dependabot[bot]@users.noreply.github.com"
           git config user.name "dependabot[bot]"
-          git add .
+          git add **/Cargo.lock
           git commit -am "update all Cargo files"
           git push