[gh actions] Split os test matrix

Split the build matrix into OS specific builds. OS specific errors
should now not auto-stop the tests on other OS builds.

Author: mpsonntag

.github/workflows/run-tests.yml

@@ -8,11 +8,51 @@ on:
     branches:
       - master
 jobs:
-  tests:
+  linux_tests:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-latest, macos-latest, windows-latest]
+        os: [ubuntu-latest]
+        python-version: [3.6, 3.7, 3.8, 3.9]
+    steps:
+      - uses: actions/checkout@v2
+      - name: Setup Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Display Python version
+        run: python -c "import sys; print(sys.version)"
+      - name: Install dependencies
+        run: |
+          python setup.py install
+          pip install -r requirements-test.txt
+      - name: Run tests
+        run: pytest
+  mac_tests:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [macos-latest]
+        python-version: [3.6, 3.7, 3.8, 3.9]
+    steps:
+      - uses: actions/checkout@v2
+      - name: Setup Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Display Python version
+        run: python -c "import sys; print(sys.version)"
+      - name: Install dependencies
+        run: |
+          python setup.py install
+          pip install -r requirements-test.txt
+      - name: Run tests
+        run: pytest
+  win_tests:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [windows-latest]
         python-version: [3.6, 3.7, 3.8, 3.9]
     steps:
       - uses: actions/checkout@v2