Remove dependency on dateutil
iso8601 is good enough, according to !98 (closed)#inline-49609
Also fix incorrect type annotations and test.
Depends on !98 (closed).
Migrated from D6912 (view on Phabricator)
Staging instance, all changes can be removed at any time
iso8601 is good enough, according to !98 (closed)#inline-49609
Also fix incorrect type annotations and test.
Depends on !98 (closed).
Migrated from D6912 (view on Phabricator)