Fix python 3.9 syntax for entry_points

src/dxtbx/format/Registry.py

@@ -7,6 +7,7 @@
 
 import importlib.metadata
 import os
+import sys
 import typing
 from typing import Callable
 
@@ -34,7 +35,13 @@ def get_format_class_index() -> dict[str, tuple[Callable[[], type[Format]], list
     """
     if not hasattr(get_format_class_index, "cache"):
         class_index = {}
-        for e in importlib.metadata.entry_points(group="dxtbx.format"):
+        if sys.version_info < (3, 10):
+            # REMOVE when python 3.10 is minimum.
+            # This was was deprecated in 3.10, and removed in 3.12.
+            format_ep = importlib.metadata.entry_points()["dxtbx.format"]
+        else:
+            format_ep = importlib.metadata.entry_points(group="dxtbx.format")
+        for e in format_ep:
             if ":" in e.name:
                 format_name, base_classes_str = e.name.split(":", 1)
                 base_classes = tuple(base_classes_str.split(","))