Upgrade to Python 3.10.

Shapely doesn't have a Windows wheel on pypi yet, but we can get them
from https://www.lfd.uci.edu/~gohlke/pythonlibs/#shapely. This unblocks
(and because wheels are matched to python versions, *requires*)
upgrading to Python 3.10.

.github/workflows/test.yml

@@ -3,31 +3,30 @@ name: Test
 on: [push, pull_request]
 
 jobs:
-
   build:
     runs-on: windows-latest
     steps:
-    - uses: actions/checkout@v2
-      with:
-        submodules: true
+      - uses: actions/checkout@v2
+        with:
+          submodules: true
 
-    - name: Set up Python 3.9
-      uses: actions/setup-python@v2
-      with:
-        python-version: 3.9
+      - name: Set up Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: "3.10"
 
-    - name: Install environment
-      run: |
-        python -m venv ./venv
+      - name: Install environment
+        run: |
+          python -m venv ./venv
 
-    - name: Install dependencies
-      run: |
-        ./venv/scripts/activate
-        python -m pip install -r requirements.txt
-        # For some reason the shiboken2.abi3.dll is not found properly, so I copy it instead
-        Copy-Item .\venv\Lib\site-packages\shiboken2\shiboken2.abi3.dll .\venv\Lib\site-packages\PySide2\ -Force
+      - name: Install dependencies
+        run: |
+          ./venv/scripts/activate
+          python -m pip install -r requirements.txt
+          # For some reason the shiboken2.abi3.dll is not found properly, so I copy it instead
+          Copy-Item .\venv\Lib\site-packages\shiboken2\shiboken2.abi3.dll .\venv\Lib\site-packages\PySide2\ -Force
 
-    - name: run tests
-      run: |
-        ./venv/scripts/activate
-        pytest tests
+      - name: run tests
+        run: |
+          ./venv/scripts/activate
+          pytest tests