v0.6.2a3

Fixed

• All Scrapy versions — unified async dispatch in BaseEngine.fetch
  Scrapy routes async downloader middlewares through one of two runners depending on
  the version, and each runner requires a different awaitable type:

  Scrapy path	Runner	Needs
  ensure_awaitable (newer Scrapy, local)	asyncio Task	asyncio.Future (run_in_executor)
  deferred_from_coro (Zyte scrapy:2.11–2.12)	Twisted _inlineCallbacks	Twisted Deferred (deferToThread)

  BaseEngine.fetch now detects the active runner via asyncio.get_running_loop():
  if a running loop is found (asyncio Task context) it uses loop.run_in_executor;
  if RuntimeError is raised (no asyncio Task, Twisted _inlineCallbacks context)
  it falls back to deferToThread. This replaces the single-strategy implementations
  from a2 that each fixed one path but broke the other.