Use Python 3.10

Python 3.11 had a breaking change which breezy is not compatible with.

Author: Flamefire

.github/workflows/synchronize-launchpad.yml

@@ -13,6 +13,9 @@ jobs:
   upload:
     runs-on: ubuntu-latest
     steps:
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.10'
       - name: Install dependencies
         run: |
           venv_dir="/tmp/venv"