Run against regular python3.10.

.github/workflows/pythonpackage.yml

@@ -13,7 +13,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        python-version: [3.6, 3.7, 3.8, 3.9, 3.10-dev, pypy3]
+        python-version: [3.6, 3.7, 3.8, 3.9, 3.10, pypy3]
         exclude:
           # sqlite3 exit handling seems to get in the way
           - os: macos-latest