Fix dict[str, Any] serialization

    When a dict inside a class had values of type Any and the
    dict contained non-primitive types, pyserde would enter
    an infinite recusion.  See #617 for details.

    The fix here causes non-primitive values to be serialized
    as strings when calling to_dict.  Arguably, this loses
    information, as a dict should be able to store the values
    without serializing them to strings first.  However, this
    same behavior exists when a dataclass variable is typed
    as Any and contains a non-primitive object (pyserde
    serializes it to a string):

    ```
    import serde
    import uuid
    from typing import Any

    @serde.serde
    class A:
        a: Any

    foo = A(uuid.UUID('05b69d9a-3783-46ea-a811-35fa4b72ddac'))
    print(to_dict(a))  # {'a': '05b69d9a-3783-46ea-a811-35fa4b72ddac'}
    ```

serde/se.py

@@ -381,8 +381,9 @@ def serializable_to_obj(object: Any) -> Any:
         elif is_bearable(o, dict):
             return {k: thisfunc(v) for k, v in o.items()}
         elif is_str_serializable_instance(o) or is_datetime_instance(o):
+            se_cls = o.__class__ if not c or c is Any else c
             return CACHE.serialize(
-                c or o.__class__,
+                se_cls,
                 o,
                 reuse_instances=reuse_instances,
                 convert_sets=convert_sets,

tests/test_basics.py

@@ -662,7 +662,6 @@ class Foo:
 
 @pytest.mark.parametrize("se,de", format_msgpack)
 def test_inheritance(se, de):
-
     @serde.serde
     class Base:
         a: int
@@ -1113,3 +1112,23 @@ class Foo:
         a: int = serde.field(skip=True)
 
     assert serde.to_dict(Foo(10)) == {}
+
+
+def test_dict_str_any() -> None:
+    @serde.serde
+    class Foo:
+        a: dict[str, Any]
+
+    # Because the dict values are typed as Any, all values will be serialized as strings
+    date = datetime.datetime(2024, 12, 3, 16, 55, 20, 220662)
+    date_str = date.isoformat()
+
+    uuid_val = uuid.UUID("efb71d76-4337-4b27-a612-5b6f95b01d42")
+    uuid_str = str(uuid_val)
+
+    foo = Foo(a={"a": uuid_val, "b": date})
+    foo_se = {"a": {"a": uuid_str, "b": date_str}}
+    foo_de = Foo(a={"a": uuid_str, "b": date_str})
+
+    assert serde.to_dict(foo) == foo_se
+    assert serde.from_dict(Foo, foo_se) == foo_de