tests/test-gendoc-zh_TW.t

patchbomb: use email.encoders instead of email.Encoders

No idea when this became a thing, but it exists for me in both 2.7 and 3.6.

Differential Revision: https://phab.mercurial-scm.org/D4222

#require docutils gettext

  $ $TESTDIR/check-gendoc zh_TW
  checking for parse errors