Merge pull request #737 from opensafely-core/test-in-3.10

Test under python 3.10

.github/workflows/tests.yml

@@ -26,11 +26,11 @@ jobs:
   test-job:
     strategy:
       matrix:
-        os: [ubuntu-20.04, windows-2019, macos-12]
+        os: [ubuntu-20.04, ubuntu-22.04, windows-2019, macos-12]
         # Python 3.8 is what we currently support for running cohortextractor
         # locally, and 3.9 is what we required for databuilder so we need to make
         # sure we can run with those
-        python: [3.8, 3.9]
+        python: ["3.8", "3.9", "3.10"]
     runs-on: ${{ matrix.os }}
     name: Run test suite
     steps: