Drop Python 3.5 and add Pypy and other OSs to the build matrix

Author: filmor

.github/workflows/ci.yml

@@ -1,7 +1,7 @@
 # This workflow will install Python dependencies, run tests and lint with a variety of Python versions
 # For more information see: https://help.github.com/actions/language-and-framework-guides/using-python-with-github-actions
 
-name: Python package
+name: Python Tests
 
 on:
   push:
@@ -11,17 +11,18 @@ on:
 
 jobs:
   build:
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        python-version: [3.5, 3.6, 3.7, 3.8, 3.9]
+        os: [ubuntu-latest, windows-latest, macos-latest]
+        python: ['3.9', '3.8', '3.7', '3.6', pypy3]
 
     steps:
     - uses: actions/checkout@v2
-    - name: Set up Python ${{ matrix.python-version }}
+    - name: Set up Python ${{ matrix.python }}
       uses: actions/setup-python@v2
       with:
-        python-version: ${{ matrix.python-version }}
+        python-version: ${{ matrix.python }}
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip