fix #378, loosen SQLAlchemy version requirement

wwwjfy · wwwjfy · commit f39aa6b1adef · 2018-11-04T22:54:22.000+08:00
diff --git a/requirements.txt b/requirements.txt
@@ -1,3 +1,3 @@
 asyncpg==0.18.1
-SQLAlchemy==1.2.12
+SQLAlchemy>=1.2
 aiocontextvars==0.2.1
