chore(deps): update actions/checkout action to v6 (#18)

Author: renovate[bot]

.github/workflows/test-template.yml

@@ -13,7 +13,7 @@ jobs:
     env:
       PROJECT_NAME: mytemplate
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: cargo-generate/cargo-generate-action@v0.20.0
         with:
           name: ${{ env.PROJECT_NAME }}