Fix close-issues workflow permissions

- Add contents: read permission for checkout
- Use github.token instead of secrets.GITHUB_TOKEN

Author: thdxr

.github/workflows/close-issues.yml

@@ -9,6 +9,7 @@ jobs:
   close:
     runs-on: ubuntu-latest
     permissions:
+      contents: read
       issues: write
     steps:
       - uses: actions/checkout@v4
@@ -19,5 +20,5 @@ jobs:
 
       - name: Close stale issues
         env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GITHUB_TOKEN: ${{ github.token }}
         run: bun script/github/close-issues.ts