Include conftest.py in sdists (dask#9115)

musicinmybrain · web-flow · commit 3148b14bc79e · 2022-05-24T11:01:39.000-05:00
Since sdists include the tests, and conftest.py is needed to run them,
it should be included.
diff --git a/MANIFEST.in b/MANIFEST.in
@@ -12,3 +12,5 @@ include dask/py.typed
 
 include versioneer.py
 include dask/_version.py
+
+include conftest.py
