Fix PostgreSQL array type

Fixes #188.

Signed-off-by: Anders Kaseorg <andersk@mit.edu>

sqlalchemy-stubs/dialects/postgresql/array.pyi

@@ -1,5 +1,5 @@
-from typing import Any as _AnyType, Optional, TypeVar, Type, Callable, overload
-from ...sql import expression
+from typing import Any as _AnyType, Optional, Sequence, TypeVar, Type, Union, Callable, overload
+from ...sql import ColumnElement, expression
 from ...sql.type_api import TypeEngine
 from ... import types as _sqltypes
 
@@ -8,7 +8,14 @@ _T = TypeVar('_T')
 def Any(other: _AnyType, arrexpr: _AnyType, operator: Callable[..., _AnyType] = ...) -> _AnyType: ...
 def All(other: _AnyType, arrexpr: _AnyType, operator: Callable[..., _AnyType] = ...) -> _AnyType: ...
 
-class array(expression.Tuple): ...
+class array(expression.Tuple[_T]):
+    def __init__(
+        self,
+        clauses: Sequence[Union[_T, ColumnElement[_T]]],
+        type_: Optional[Union[TypeEngine[_T], Type[TypeEngine[_T]]]] = ...,
+        **kw: _AnyType,
+    ) -> None: ...
+
 class ARRAY(_sqltypes.ARRAY[_T]):
     @overload
     def __init__(self, item_type: TypeEngine[_T], as_tuple: bool = ..., dimensions: Optional[_AnyType] = ...,