Update rocket.chat

Changes:

- https://github.com/RocketChat/Docker.Official.Image/commit/608da87: Update to 1.3.1

library/rocket.chat

@@ -1,5 +1,5 @@
 Maintainers: Rocket.Chat Image Team <[email protected]> (@RocketChat)
 GitRepo: https://github.com/RocketChat/Docker.Official.Image.git
 
-Tags: 1.3.0, 1.3, 1, latest
-GitCommit: fcee8e1be13a5bbcfd34441e28dc96c0f56446b1
+Tags: 1.3.1, 1.3, 1, latest
+GitCommit: 608da876a8d8b20dfba29528b29ca49aab9d243f