Fix: more detail ubuntu version

Author: digitalisx

.github/workflows/test.yaml

@@ -3,10 +3,10 @@ on: [push, pull_request]
 jobs:
 
   build:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     strategy:
       matrix:
-        python-version: ["3.6.7"]
+        python-version: ["3.6"]
     steps:
     - uses: actions/checkout@v3
     - name: Set up Python ${{ matrix.python-version }}