Updates build config to test in Python 3.10

This makes the repo compatible with clu>=0.0.10 that dropped support for Python 3.9:

https://github.com/google/CommonLoopUtils/releases/tag/v0.0.10

PiperOrigin-RevId: 580102944

.github/workflows/build.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: [3.8]
+        python-version: [3.10]
     steps:
     - name: Cancel previous
       uses: styfle/cancel-workflow-action@0.8.0