python 3.10 (#193)

python 3.10 is released and generally available

Author: dulmandakh

.github/workflows/ci.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        python-version: ["3.6", "3.7", "3.8", "3.9", "3.10-dev"]
+        python-version: ["3.6", "3.7", "3.8", "3.9", "3.10"]
         os: [ubuntu-latest]
 
     steps: