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)
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)