Fix incompatibility with Twisted < 21. (#10713)

Turns out that the functionality added in #10546 to skip TLS was incompatible
with older Twisted versions, so we need to be a bit more inventive.

Also, add a test to (hopefully) not break this in future. Sadly, testing TLS is
really hard.

1 files changed, 1 insertions, 0 deletions

diff --git a/mypy.ini b/mypy.ini

index e1b9405daa..349efe37bb 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -87,6 +87,7 @@ files =
   tests/test_utils,
   tests/handlers/test_password_providers.py,
   tests/handlers/test_room_summary.py,
+  tests/handlers/test_send_email.py,
   tests/rest/client/v1/test_login.py,
   tests/rest/client/v2_alpha/test_auth.py,
   tests/util/test_itertools.py,