Explicitly format the enum as ClassName.FieldName.

Context: Python 3.11 changed the `__str__()` value of `IntEnum`, `IntFlag`, and `StrEnum` to be their _value_'s `__str__()`. e.g. `str(SomeIntEnum.A) == "1"` in Python 3.11+, but `str(SomeIntEnum.A) == "SomeIntEnum.A"` before.

This change makes the formatting consistent.

PiperOrigin-RevId: 546304776

gin/config.py

@@ -2830,7 +2830,7 @@ def decorator(cls, module=module):
     if module is None:
       module = cls.__module__
     for value in cls:
-      constant('{}.{}'.format(module, str(value)), value)
+      constant('{}.{}.{}'.format(module, cls.__name__, value.name), value)
     return cls
 
   if cls is None:

tests/config_test.py

@@ -2378,19 +2378,26 @@ class SomeEnum(enum.Enum):
       A = 0,
       B = 1
 
+    @config.constants_from_enum(module='enum_module')
+    class SomeIntEnum(enum.IntEnum):
+      A = 0
+      B = 1
+
     @config.configurable
-    def f(a, b):
-      return a, b
+    def f(a, b, c):
+      return a, b, c
 
     config.parse_config("""
       f.a = %enum_module.SomeEnum.A
       f.b = %SomeEnum.B
+      f.c = %SomeIntEnum.A
     """)
     # pylint: disable=no-value-for-parameter
-    a, b = f()
+    a, b, c = f()
     # pylint: enable=no-value-for-parameter
     self.assertEqual(SomeEnum.A, a)
     self.assertEqual(SomeEnum.B, b)
+    self.assertEqual(SomeIntEnum.A, c)
 
   def testConstantsFromEnumWithModule(self):