Asynchronous start method compatible with new Scrapy versions

[lexxai]

import asyncio

class RedisMixin:   

...
     async def start(self):
        """Asynchronous start method compatible with new Scrapy versions."""
        for req in await asyncio.to_thread(self._collect_start_requests):
            yield req

    def _collect_start_requests(self):
        """Collect start requests synchronously from next_requests()."""
        return list(self.next_requests())  # collect all yielded requests