Fix _get_time_slice() end_time format when years <1000

Author: tomvothecoder

e3sm_diags/driver/utils/dataset_xr.py

@@ -1254,7 +1254,9 @@ def _get_time_slice(self, ds: xr.Dataset, filename: str) -> slice:
 
         if self.is_sub_monthly:
             start_time = f"{start_yr_str}-01-01"
-            end_time = f"{str(int(end_yr_str) + 1)}-01-01"
+
+            end_yr_str = str(int(end_yr_str) + 1).zfill(4)
+            end_time = f"{end_yr_str}-01-01"
         else:
             start_time = self._get_slice_with_bounds(ds, start_yr_str, "start")
             end_time = self._get_slice_with_bounds(ds, end_yr_str, "end")