delete pull_request.yml

.github/workflows/pull_request.yml

-#name: Pull Request
-#
-#on: [pull_request]
-#
-#jobs:
-#  pre-commit:
-#    runs-on: ubuntu-20.04
-#    steps:
-#      - uses: actions/checkout@v3
-#      - uses: actions/setup-python@v4
-#        with:
-#          python-version: 3.9
-#      - uses: pre-commit/action@v2.0.3