edf2nx: adapt to deprecation warning code by trying to import get_flats_url function first

nxtomomill/converter/edf/edfconverter.py

@@ -152,7 +152,11 @@ def edf_to_nx(
                 _edf_to_ignore.append("HST")
             else:
                 _edf_to_ignore.remove("HST")
-            refs_urls = scan.get_refs_url(
+            try:
+                get_flats_url = scan.get_flats_url
+            except ImportError:
+                get_flats_url = scan.get_refs_url
+            refs_urls = get_flats_url(
                 scan_path=scan.path, prefix=refs_to_find, ignore=_edf_to_ignore
             )
             if len(refs_urls) > 0: