add axis to segment. This stops the super annoying 'could not certify axis coords' warning from MOM6

Author: ashjbarnes

regional_mom6/regional_mom6.py

@@ -2887,6 +2887,9 @@ def regrid_velocity_tracers(
         # If repeat-year forcing, add modulo coordinate
         if self.repeat_year_forcing:
             segment_out["time"] = segment_out["time"].assign_attrs({"modulo": " "})
+        # Add axes to suppress annoying runtime warnings
+        segment_out[f"ny_{self.segment_name}"] = segment_out[f"ny_{self.segment_name}"].assign_attrs({"axis":"Y"})
+        segment_out[f"nx_{self.segment_name}"] = segment_out[f"nx_{self.segment_name}"].assign_attrs({"axis":"X"})
         segment_out.load().to_netcdf(
             self.outfolder / f"forcing_obc_{self.segment_name}.nc",
             encoding=encoding_dict,