Update psycopg2-binary to 2.9.3.

requirements.txt

@@ -8,5 +8,5 @@ redis==3.2.1
 sqlparse==0.3.0
 flake8==3.7.7
 coverage==4.5.3
-psycopg2-binary==2.8.2
+psycopg2-binary==2.9.3
 kombu==4.5.0