Replace the usage of deprecated imp module in order to work with Py…

…thon 3.12.

Fixes: google#24.
PiperOrigin-RevId: 641152140
Change-Id: Ide2d88b5fdbe804617495df129176c3692033d45

ml_collections/config_flags/config_flags.py

@@ -20,18 +20,20 @@
 import enum
 import errno
 import functools as ft
-import imp
+import importlib.machinery
 import os
 import re
 import sys
 import traceback
+import types
 from typing import Any, Callable, Dict, Generic, List, MutableMapping, Optional, Sequence, Tuple, Type, TypeVar
 
 from absl import flags
 from absl import logging
 from ml_collections import config_dict
 from ml_collections.config_flags import config_path
 from ml_collections.config_flags import tuple_parser
+
 FLAGS = flags.FLAGS
 
 # Forward for backwards compatibility.
@@ -43,6 +45,20 @@
 flags._helpers.disclaim_module_ids.add(id(sys.modules[__name__]))  # pylint: disable=protected-access
 
 
+def _load_source(module_name: str, module_path: str) -> types.ModuleType:
+  """Loads a Python module from its source file.
+
+  Args:
+    module_name: name of the module in sys.modules.
+    module_path: path to the Python file containing the module.
+
+  Returns:
+    The loaded Python module.
+  """
+  loader = importlib.machinery.SourceFileLoader(module_name, module_path)
+  return loader.load_module()
+
+
 class _LiteralParser(flags.ArgumentParser):
   """Parse arbitrary built-in (`--cfg.val=1`, `--cfg.val="[1, 2, {}]"`,...)."""
 
@@ -560,7 +576,7 @@ def _LoadConfigModule(name: str, path: str):
 
   # Works for relative paths.
   with ignoring_errors.Attempt('Relative path', path):
-    config_module = imp.load_source(name, path)
+    config_module = _load_source(name, path)
     return config_module
 
   # Nothing worked. Log the paths that were attempted.