Test more older Python versions

Author: tcalmant

.github/workflows/build-20.04.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: CI Build - Python 3.7
+name: CI Build - Python 3.4-3.7
 
 on:
   push:
@@ -17,7 +17,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.7"]
+        python-version: ["3.4", "3.5", "3.6", "3.7"]
 
     steps:
     - uses: actions/checkout@v4