[test] Split download tests so they can be more easily run in CI

.github/workflows/download.yml

@@ -1,15 +1,31 @@
 name: Download Tests
 on: [push, pull_request]
 jobs:
-  tests:
+  quick:
-    name: Download Tests
+    name: Quick Download Tests
     if: "contains(github.event.head_commit.message, 'ci run dl')"
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up Python
+      uses: actions/setup-python@v2
+      with:
+        python-version: 3.9
+    - name: Install test requirements
+      run: pip install pytest
+    - name: Run tests
+      continue-on-error: true
+      run: ./devscripts/run_tests.sh download
+
+  full:
+    name: Full Download Tests
+    if: "contains(github.event.head_commit.message, 'ci run dl all')"
     runs-on: ${{ matrix.os }}
     strategy:
       fail-fast: true
       matrix:
         os: [ubuntu-latest]
-        python-version: ['3.6', '3.7', '3.9', '3.10', 3.11-dev, pypy-3.6, pypy-3.7, pypy-3.8]
+        python-version: ['3.6', '3.7', '3.10', 3.11-dev, pypy-3.6, pypy-3.7, pypy-3.8]
         run-tests-ext: [sh]
         include:
         # atleast one of each CPython/PyPy tests must be in windows