sqlalchemy func.current_timestamp missing doc

### Describe the Bug

on hover shows

```
(method) current_timestamp: def current_timestamp(
self: current_timestamp,
*args: _ColumnExpressionArgument,
**kwargs: Any
) -> None: ...
```

go to def

```
@property
def current_timestamp(self) -> Type[current_timestamp]: ...
```

hover on the right `current_timestamp` gives

```
(class) current_timestamp: type[current_timestamp]
The CURRENT_TIMESTAMP() SQL function.
```

### Sandbox Link

_No response_

### (Only applicable for extension issues) IDE Information

_No response_