run download tests on a daily schedule (#2675)

* run download tests on a daily schedule

* add blank line

* add issue template as workflow trigger

* try broaden workflow triggers

* run scheduled test after nightlies are published

* try remove schedule as workflow trigger

* restore workflow triggers

* cleanup

* Revert "remove dummy workflow"

This reverts commit d094e4bf2c3da2392bf1298450b97d9d63a15bfc.

* cleanup

.github/failed_schedule_issue_template.md

+---
+title: Scheduled workflow {{ env.WORKFLOW }}/{{ env.JOB }} failed
+labels: bug, module: datasets
+---
+
+Oh no, something went wrong in the scheduled workflow {{ env.WORKFLOW }}/{{ env.JOB }}. 
+Please look into it:
+
+https://github.com/{{ env.REPO }}/actions/runs/{{ env.ID }}
+
+Feel free to close this if this was just a one-off error.

.github/workflows/tests-schedule.yml

+name: tests
+
+on:
+  pull_request:
+    - "test/test_datasets_download.py"
+    - ".github/failed_schedule_issue_template.md"
+    - ".github/workflows/tests-schedule.yml"
+
+  schedule:
+    - cron: "0 9 * * *"
+
+jobs:
+  download:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Set up python
+        uses: actions/setup-python@v2
+        with:
+          python-version: 3.6
+
+      - name: Upgrade pip
+        run: python -m pip install --upgrade pip
+
+      - name: Install PyTorch from the nightlies
+        run: |
+          pip install numpy
+          pip install --pre torch torchvision -f https://download.pytorch.org/whl/nightly/cpu/torch_nightly.html
+
+      - name: Install tests requirements
+        run: pip install pytest pytest-subtests
+
+      - name: Run tests
+        run: pytest test/test_datasets_download.py
+
+      - uses: JasonEtco/create-an-issue@v2.4.0
+        name: Create issue if download tests failed
+        if: failure()
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          REPO: ${{ github.repository }}
+          WORKFLOW: ${{ github.workflow }}
+          JOB: ${{ github.job }}
+          ID: ${{ github.run_id }}
+        with:
+          filename: .github/failed_schedule_issue_template.md