test with mongodb 4.1

Author: dcrosta

tox.ini

@@ -2,14 +2,15 @@
 
 ; keep the pymongo list in sync with what's in .travis.yaml
 envlist=
-    pymongo{30,31,32,33,34,35,36,37}-mongo{32,34,36,40}-flask{0_11,0_12,10}, style
+    pymongo{30,31,32,33,34,35,36,37}-mongo{32,34,36,40,41}-flask{0_11,0_12,10}, style
 
 [testenv]
 docker =
     mongo32: mongo:3.2
     mongo34: mongo:3.4
     mongo36: mongo:3.6
     mongo40: mongo:4.0
+    mongo41: mongo:4.1
 
 deps =
     pytest