gh-118761: Improve import time of tomllib (#128907)

Improve import time of `tomllib`  (in sync with upstream)

Lib/test/test_tomllib/test_misc.py

@@ -5,6 +5,7 @@
 import copy
 import datetime
 from decimal import Decimal as D
+import importlib
 from pathlib import Path
 import sys
 import tempfile
@@ -113,3 +114,11 @@ class TestMiscellaneous(unittest.TestCase):
                               nest_count=nest_count):
                 recursive_table_toml = nest_count * "key = {" + nest_count * "}"
                 tomllib.loads(recursive_table_toml)
+
+    def test_types_import(self):
+        """Test that `_types` module runs.
+
+        The module is for type annotations only, so it is otherwise
+        never imported by tests.
+        """
+        importlib.import_module(f"{tomllib.__name__}._types")