GitHub CI: Disable/remove set_pr_labels

.github/workflows/set_pr_labels.yml

@@ -1,36 +0,0 @@
-name: Pull Requests
-on:
-  schedule:
-    - cron: '0 */4 * * *'
-
-jobs:
-  Set-Labels:
-    runs-on: ubuntu-18.04
-    steps:
-      - uses: actions/checkout@v2
-
-      - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v1
-        with:
-          python-version: 3.6
-
-      - name: Cache pip
-        uses: actions/cache@v1
-        with:
-          path: ~/.cache/pip
-          key: ${{ runner.os }}-pip-${{ hashFiles('.github/org_control/requirements*.txt') }}
-          restore-keys: |
-            ${{ runner.os }}-pip-
-            ${{ runner.os }}-
-
-      - name: Install dependencies
-        run: |
-          pip install -r requirements.txt
-        working-directory: .github/org_control
-
-      - name: Check PRs
-        run: |
-          python3 check_pr.py
-        env:
-          GITHUB_TOKEN: ${{ secrets.CI }}
-        working-directory: .github/org_control