limit to aioredis 1.x (#59)

Author: djmitche

tests/requirements/sanic.txt

@@ -1,7 +1,7 @@
 # these are constrained by the files in tests/constraints/*.txt
 # to support a triple stack Django/Flask/Sanic
 aiohttp
-aioredis
+aioredis<2.0.0
 Sanic
 sanic_redis
 uvloop>=0.14.0rc1