Added container to workflow

Author: BasMonkey

.github/workflows/exoncov.yml

@@ -18,10 +18,12 @@ jobs:
   build:
 
     runs-on: ubuntu-20.04
+    container:
+        image: python:2.7.18-buster
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["2.8"]
+        python-version: ["2.7"]
 
     steps:
     - uses: actions/checkout@v3