Updated main.yml

Author: fedos3d

.github/workflows/main.yml

@@ -1,8 +1,8 @@
 name: GitHub Actions Demo
 on: [push]
 jobs:
-  JOB_TO_TEST_PYTHON
-  runs-on: ubuntu-latest
+ TEST_PYTHON:
+  runs-on: ubuntu-20.04
   steps:
    - name: Check out repository code
      uses: actions/checkout@v2