Run tests on multiple operating systems

Supporing only
- ubuntu
- centos
- debian

Author: shiplu

.github/workflows/ci.yml

@@ -18,14 +18,24 @@ env:
 
 jobs:
   test:
-    runs-on: ubuntu-18.04
-
+    runs-on: ubuntu-20.04
     strategy:
       matrix:
         python-version:
         - 2.7
         - 3.6
+        - 3.7
+        - 3.8
+        - 3.9
+        os:
+        - centos:7
+        - centos:8
+        - ubuntu:bionic
+        - ubuntu:focal
+        - debian:stretch
+        - debian:buster
 
+    container: ${{ matrix.os }}
     steps:
     - name: Setup python ${{ matrix.python-version }}
       uses: actions/setup-python@v2