Update build-ci.yml

Author: pgleeson

.github/workflows/build-ci.yml

@@ -13,7 +13,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: [ "3.9" ]
+        python-version: [ "3.8" ]
 
     steps:
     - uses: actions/checkout@v2