Exclude Pytest 8.2 from setup.cfg

We cannot use pytest-async 0.23 because of pytest-dev/pytest-asyncio#706
We need to use pytest-async 0.23 if we use pytest 8.2 because of pytest-dev/pytest#12269
This may be fixed bt this backport of the fix in pytest-async 0.23: pytest-dev/pytest-asyncio#823

setup.cfg

@@ -122,7 +122,7 @@ tests =
     pytest-xdist>=2
     pytest-env>=0.6.2
     pytest-mock>=3.7
-    pytest>=6
+    pytest>=6,!=8.2.*
     testfixtures>=6.11.0
     towncrier>=23
     # Type annotation stubs