test: a reader's zone comes from their account; a London expiry reads BST or GMT (#6350)

The change-form test set the zone on the session, which the auth middleware
resets from the account on every request. The password reset test asserted
BST, which stopped being London's zone name on 25 Oct.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/integration/test_passwords.py

@@ -162,7 +162,8 @@ def test_a_forgotten_password_is_reset_from_the_emailed_link(app, monkeypatch):
         mine = to(sent, f"{name}@example.com", f"{sso_name}@example.com", f"nobody-{uid[:8]}@example.com")
         assert [m["To"] for m in mine] == [f"{name}@example.com"]
         text = mine[0].get_body(("plain",)).get_content()
-        assert name in text and "BST" in text
+        # In the account's zone, not UTC: London's name for it, summer or winter.
+        assert name in text and re.search(r"\d\d:\d\d (BST|GMT)\b", text)
         key = _KEY.search(text).group(1)
 
         page = await (await guest.get(f"/reset/{key}")).get_data(as_text=True)