[io] update dicttonx to latest API

est/io/io.py

@@ -484,7 +484,7 @@ def write_xas_proc(
         if plot.silx_style is not None:
             nexus_dict["@SILX_style"] = json.dumps(plot.silx_style)
 
-        dicttonx(nexus_dict, h5_file, mode="a", h5path=plot_path, existing="overwrite")
+        dicttonx(nexus_dict, h5_file, mode="a", h5path=plot_path, update_mode="replace")
 
     # save plots
     for i_plot, plot in enumerate(plots):
@@ -498,7 +498,9 @@ def write_xas_proc(
             "@NX_class": "NXdata",
             "@default": "plot_0",
         }
-        dicttonx(nexus_dict, h5_file, mode="a", h5path=plots_path, existing="overwrite")
+        dicttonx(
+            nexus_dict, h5_file, mode="a", h5path=plots_path, update_mode="replace"
+        )
 
     if process.getConfiguration() is not None:
         h5_path = "/".join((nx_process_path, "configuration"))
@@ -566,11 +568,11 @@ def write_xas(
     }
     if overwrite:
         mode = "w"
-        existing = "overwrite"
+        update_mode = "replace"
     else:
         mode = "a"
-        existing = "add"
-    dicttonx(nx_dict, h5_file, h5path=h5path, mode=mode, existing=existing)
+        update_mode = "add"
+    dicttonx(nx_dict, h5_file, h5path=h5path, mode=mode, update_mode=update_mode)
 
 
 def write_spectrum_saving_pt(h5_file, entry, obj, overwrite=True):