Skip test_additional_requests_dont_filter_offsite on Scrapy versions where the offside middleware is still a spider middleware

Author: Gallaecio

tests/test_downloader.py

@@ -395,6 +395,8 @@ async def parse(self, response, page: ItemPage):
 
 @inlineCallbacks
 def test_additional_requests_dont_filter_offsite() -> None:
+    pytest.importorskip("scrapy.downloadermiddlewares.offsite")
+
     items = []
 
     with MockServer(EchoResource) as server: