add Python 3.10 to CI tests, remove Python 3.8

PiperOrigin-RevId: 531222782

Author: shoyer

.github/workflows/ci-build.yml

@@ -16,7 +16,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.8", "3.9"]
+        python-version: ["3.9", "3.10"]
     steps:
     - name: Cancel previous
       uses: styfle/[email protected]