fix(smtp): simplify PQC warning detail message and bump quantumvalidator submodule

Author: t0kubetsu

mailvalidator/checks/smtp/_pqc.py

@@ -102,9 +102,7 @@ def _check_pqc(host: str, port: int, checks: list[CheckResult]) -> None:
             )
         )
     else:
-        details = ["No post-quantum hybrid group negotiated."]
-        if kex_check:
-            details.append(kex_check.reason)
+        details = [kex_check.reason if kex_check else "No post-quantum hybrid group negotiated."]
         checks.append(
             CheckResult(
                 name="PQC Key Exchange",

tests/checks/test_pqc.py

@@ -150,8 +150,7 @@ def test_warning_status_with_kex_reason(self):
         assert cr.name == "PQC Key Exchange"
         assert cr.status == Status.WARNING
         assert cr.value == "x25519"
-        assert "No post-quantum hybrid group negotiated." in cr.details
-        assert any("X25519MLKEM768" in d for d in cr.details)
+        assert cr.details == ["No PQC hybrid group; got x25519. Enable X25519MLKEM768."]
 
     def test_warning_none_group(self):
         checks: list = []