fix: Expand VersionedUnionType tuple in SchemaUnion definition

Fixes ImportError caused by passing a tuple to Union[]. The previous
commit (e290f46) changed VersionedUnionType from a Union type to a
tuple for isinstance checks, but SchemaUnion was still trying to use
it as a Union argument. This expands the tuple elements individually
for Python 3.10+ (UnionType + _UnionGenericAlias) and Python < 3.10
(_UnionGenericAlias only).

Error: TypeError: Union[arg, ...]: each arg must be a type. Got
(<class 'types.UnionType'>, <class 'typing._UnionGenericAlias'>).

Author: miettal

google/genai/types.py

@@ -4251,9 +4251,14 @@ class ToolDict(TypedDict, total=False):
 ToolListUnion = list[ToolUnion]
 ToolListUnionDict = list[ToolUnionDict]
 
-SchemaUnion = Union[
-    dict[Any, Any], type, Schema, builtin_types.GenericAlias, VersionedUnionType  # type: ignore[valid-type]
-]
+if sys.version_info >= (3, 10):
+  SchemaUnion = Union[
+      dict[Any, Any], type, Schema, builtin_types.GenericAlias, builtin_types.UnionType, type(Union[int, str])
+  ]
+else:
+  SchemaUnion = Union[
+      dict[Any, Any], type, Schema, builtin_types.GenericAlias, type(Union[int, str])
+  ]
 SchemaUnionDict = Union[SchemaUnion, SchemaDict]