[3.10] bpo-44676: Add ability to serialize types.Union (GH-27244) (GH-27333)

(cherry picked from commit fe13f0b0f696464dd6f283576668dbf57cb11399)

Co-authored-by: Yurii Karabas <1998uriyyo@gmail.com>
diff --git a/Lib/typing.py b/Lib/typing.py
index ffd35e5..e2fb7d1 100644
--- a/Lib/typing.py
+++ b/Lib/typing.py
@@ -321,7 +321,7 @@ def _eval_type(t, globalns, localns, recursive_guard=frozenset()):
         if isinstance(t, GenericAlias):
             return GenericAlias(t.__origin__, ev_args)
         if isinstance(t, types.Union):
-            return functools.reduce(operator.or_, ev_args)
+            return types.Union._from_args(ev_args)
         else:
             return t.copy_with(ev_args)
     return t
@@ -1800,7 +1800,7 @@ def _strip_annotations(t):
         stripped_args = tuple(_strip_annotations(a) for a in t.__args__)
         if stripped_args == t.__args__:
             return t
-        return functools.reduce(operator.or_, stripped_args)
+        return types.Union._from_args(stripped_args)
 
     return t