make strptime work well

Signed-off-by: tison <[email protected]>

src/append/rolling_file/rolling.rs

@@ -277,7 +277,7 @@ impl State {
 
                 if self.log_filename_prefix.is_none()
                     && self.log_filename_suffix.is_none()
-                    && Zoned::strptime(self.date_format, filename).is_err()
+                    && Zoned::strptime(format!("{} %:z", self.date_format), format!("{filename} +00:00")).is_err()
                 {
                     return None;
                 }