Fix broken __future__ import in IDA plugin custom_script

The first line reads `from future import __annotations__`, with the
module name and the imported symbol swapped. The intent was clearly the
PEP 563 future statement `from __future__ import annotations`.

As written, the line fails in both possible situations:

- without the third-party `future` package installed (the common case),
  the import raises `ModuleNotFoundError`, so `QILING_IDA` is never
  defined;
- with that package installed, the import silently succeeds but binds
  the module's empty `__annotations__` dict, so PEP 563 is *not*
  enabled — while the annotations in this file (`ql: Qiling`) rely on
  it, `Qiling` being imported under `TYPE_CHECKING` only.

Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01Pru9dwqPVrDakERYZwzjUx

examples/extensions/idaplugin/custom_script.py

@@ -1,4 +1,4 @@
-from future import __annotations__
+from __future__ import annotations
 
 from typing import TYPE_CHECKING, List