matrix: Fix test failure brought by the hint for usernames change.

PIG208 · Eeshan Garg · commit df60a1ac030a · 2021-06-28T11:35:54.000-02:30
Fixes a188a4e.
diff --git a/zulip/integrations/bridge_with_matrix/test_matrix.py b/zulip/integrations/bridge_with_matrix/test_matrix.py
@@ -17,7 +17,7 @@
 
 sample_config_text = """[matrix]
 host = https://matrix.org
-username = username
+username = @username@matrix.org
 password = password
 room_id = #zulip:matrix.org
 
