fix(ci): remove duplicate env key in scan_duplicate_issues workflow

The greptile suggestion in #22034 was applied without removing the
original env block, leaving a duplicate env key that makes the YAML
invalid. GitHub fails to parse the workflow on every push to main,
creating failed run entries ("No jobs were run").

.github/workflows/scan_duplicate_issues.yml

@@ -31,8 +31,6 @@ jobs:
           python-version: "3.11"
 
       - name: Scan for duplicate issues
-        env:
-          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           INPUT_THRESHOLD: ${{ inputs.threshold }}