Fix deprecated input names and remove unused GITHUB_PAT

- Use app-id/private-key instead of deprecated app_id/private_key
- Remove unused GITHUB_PAT env var (token is passed directly where needed)

Co-Authored-By: sbfnk-bot <242615673+sbfnk-bot@users.noreply.github.com>

Author: sbfnk

.github/workflows/render_readme.yml

@@ -38,15 +38,13 @@ concurrency:
 jobs:
   render-readme:
     runs-on: ubuntu-latest
-    env:
-      GITHUB_PAT: ${{ secrets.GITHUB_TOKEN }}
     steps:
       - name: Generate token
         id: generate_token
         uses: actions/create-github-app-token@v1
         with:
-          app_id: ${{ secrets.APP_ID }}
-          private_key: ${{ secrets.APP_PRIVATE_KEY }}
+          app-id: ${{ secrets.APP_ID }}
+          private-key: ${{ secrets.APP_PRIVATE_KEY }}
 
       - name: Checkout repos
         uses: actions/checkout@v6