allow test for python 3.10

Author: Licini

.github/workflows/build.yml

@@ -15,7 +15,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        python-version: ['3.6', '3.7', '3.8', '3.9']
+        python-version: ['3.6', '3.7', '3.8', '3.9', '3.10']
 
     steps:
       - uses: actions/checkout@v2