chore: fix issue

Author: ovr

rust/cubesql/pg-srv/src/values/timestamp.rs

@@ -107,8 +107,12 @@ impl ToProtocolValue for TimestampValue {
             None => self.to_naive_datetime(),
             Some(_) => self.to_fixed_datetime()?.naive_utc(),
         };
-        let ts_str = ndt.format("%Y-%m-%d %H:%M:%S%.6f").to_string();
-        ts_str.to_text(buf)
+        let as_str = ndt.format("%Y-%m-%d %H:%M:%S%.6f").to_string();
+
+        match self.tz_ref() {
+            None => as_str.to_text(buf),
+            Some(_) => (as_str + "+00").to_text(buf),
+        }
     }
 
     fn to_binary(&self, buf: &mut BytesMut) -> Result<(), ProtocolError> {