mythdbcon: force QMetaType::QDateTime values to use MythDate::kDatabase

This cares for a recent ibqt5sql5-mysql update in at least one
distribution where it isn't removing timezone information from
a query causing it to fail.

Log example without patch:
MSqlQuery::exec(DBManager16) UPDATE recorded SET recgroup = 'Deleted', recgroupid = 3 WHERE chanid = '10901' AND starttime = '2023-04-08T05:00:00.000Z' ; <<<< Took 0ms

Log example with patch:
MSqlQuery::exec(DBManager1) UPDATE recorded SET recgroup = 'Deleted', recgroupid = 3 WHERE chanid = '10901' AND starttime = '2023-04-07 05:30:00' ; <<<< Took 0ms

Results seen by users on the Forum and mailing list.

Credits to Mark, Roland and Klaas.

See: https://forum.mythtv.org/viewtopic.php?p=25833#p25833

The Debian solution is due 4/31/2023.

mythtv/libs/libmythbase/mythdbcon.cpp

@@ -881,6 +881,15 @@ bool MSqlQuery::testDBConnection()
 
 void MSqlQuery::bindValue(const QString &placeholder, const QVariant &val)
 {
+#if QT_VERSION < QT_VERSION_CHECK(6,0,0)
+    if (static_cast<QMetaType::Type>(val.type()) == QMetaType::QDateTime)
+    {
+        QSqlQuery::bindValue(placeholder,
+                             MythDate::toString(val.toDateTime(), MythDate::kDatabase),
+                             QSql::In);
+        return;
+    }
+#endif
     QSqlQuery::bindValue(placeholder, val, QSql::In);
 }
 
@@ -896,6 +905,15 @@ void MSqlQuery::bindValueNoNull(const QString &placeholder, const QVariant &val)
         QSqlQuery::bindValue(placeholder, QString(""), QSql::In);
         return;
     }
+#if QT_VERSION < QT_VERSION_CHECK(6,0,0)
+    if (type == QMetaType::QDateTime)
+    {
+        QSqlQuery::bindValue(placeholder,
+                             MythDate::toString(val.toDateTime(), MythDate::kDatabase),
+                             QSql::In);
+        return;
+    }
+#endif
     QSqlQuery::bindValue(placeholder, val, QSql::In);
 }