Use "new-style" pluggy hook wrapper

When all test failures are due to quarantined tests, we call
pytest.exit() to force a successful exit. Newer versions of pluggy emit
a `pluggy.PluggyTeardownRaisedWarning` warning due to using the
"old-style" hook wrappers. This change switches to the new style,
which eliminates the warning.

src/pytest_unflakable/_plugin.py

@@ -586,7 +586,7 @@ def _build_test_suite_run_request(
     # Allows us to override the exit code if all the failures are quarantined. We need this to be a
     # wrapper so that the default hook still gets invoked and prints the summary line with the test
     # category counts.
-    @pytest.hookimpl(hookwrapper=True, tryfirst=True)
+    @pytest.hookimpl(wrapper=True, tryfirst=True)
     def pytest_sessionfinish(
             self,
             session: pytest.Session,