global includes to ensure type inclusions in sdist

MANIFEST.in

@@ -2,4 +2,6 @@ include versioneer.py
 include redmail/_version.py
 recursive-include redmail/email/templates *.html
 recursive-include redmail/email/templates *.txt
-recursive-include redmail/test/test_files *
+recursive-include redmail/test/test_files *
+global-include *.pyi
+global-include *.typed