Move to py3.10 CI

Assuming #1444 will be merged before this one

Author: nsmith-

.github/workflows/ci.yml

@@ -36,7 +36,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, ubuntu-24.04-arm, macOS-latest, windows-latest]
-        python-version: ["3.9", "3.13"]
+        python-version: ["3.10", "3.13"]
         dask-client: ["with", "without"]
 
     name: Test (${{ matrix.os }}) - py ${{ matrix.python-version }}, ${{ matrix.dask-client }} dask