ci: Re-enable python 3.12

Now that python/cpython#105808 is fixed in beta 3.

.github/workflows/test.yml

@@ -51,9 +51,8 @@ jobs:
             tox_env: py311-full
           - python: '3.11.0'
             tox_env: py311-full
-          # 3.12 is disabled until https://github.com/python/cpython/issues/105808 is fixed
-          #- python: '3.12.0-alpha - 3.12'
-          #  tox_env: py312-full
+          - python: '3.12.0-beta.3 - 3.12'
+            tox_env: py312-full
           - python: 'pypy-3.8'
             # Pypy is a lot slower due to jit warmup costs, so don't run the
             # "full" test config there.