Start testing on Python 3.12

Closes #390

.github/workflows/main.yml

@@ -8,7 +8,8 @@ jobs:
   test:
     strategy:
       matrix:
-        python-version: [3.7, 3.8, 3.9, '3.10', 3.11]
+        # Keep this in sync with tox.ini
+        python-version: ["3.7", "3.8", "3.9", "3.10", "3.11", "3.12"]
         platform: [ubuntu-latest, macos-latest, windows-latest]
     runs-on: ${{ matrix.platform }}
     steps:
@@ -19,6 +20,7 @@ jobs:
         uses: actions/setup-python@v4
         with:
           python-version: ${{ matrix.python-version }}
+          allow-prereleases: true
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip setuptools wheel

docs/changes/390.misc

@@ -0,0 +1 @@
+Start testing in Python 3.12

tox.ini

@@ -2,7 +2,7 @@
 isolated_build = true
 envlist =
     # Keep this in sync with .github/workflows/main.yml
-    py{37,38,39,310,311}
+    py{37,38,39,310,311,312}
     formatting
     typecheck
     lint
@@ -16,6 +16,7 @@ python =
     3.9: py39
     3.10: py310
     3.11: py311, formatting, typecheck, lint, docs, release_notes
+    3.12: py312
 
 [testenv]
 extras =