fix python version

Author: xwings

.github/workflows/build-ci.yml

@@ -11,7 +11,7 @@ jobs:
       matrix:
         #os: [windows-2019, macos-10.15, ubuntu-18.04, ubuntu-20.04]
         os: [windows-2019, ubuntu-18.04, ubuntu-20.04]
-        python-version: [3.7.6, 3.9.5]
+        python-version: [3.7.6, 3.8.11]
         exclude:
           - os: ubuntu-20.04
             python-version: 3.7.6       
@@ -23,7 +23,7 @@ jobs:
           #   python-version: 3.7.6                       
         include:
           - os: ubuntu-20.04
-            python-version: 3.9.5
+            python-version: 3.8.11
             container: Docker
 
     steps: