Remove unused anthropic API key (#200)

Author: dcramer

.github/workflows/warden.yml

@@ -22,7 +22,6 @@ jobs:
         pull-requests: read
         id-token: write
     env:
-      WARDEN_ANTHROPIC_API_KEY: ${{ secrets.WARDEN_ANTHROPIC_API_KEY }}
       WARDEN_OPENROUTER_API_KEY: ${{ secrets.WARDEN_OPENROUTER_API_KEY }}
       WARDEN_MODEL: ${{ secrets.WARDEN_MODEL }}
       WARDEN_SENTRY_DSN: ${{ secrets.WARDEN_SENTRY_DSN }}