Bump loofah from 2.2.3 to 2.3.1 (#913)

Gemfile.lock

@@ -80,7 +80,7 @@ GEM
       execjs
     coffee-script-source (1.12.2)
     concurrent-ruby (1.1.5)
-    crass (1.0.4)
+    crass (1.0.5)
     createsend (4.1.2)
       hashie (~> 3.0)
       httparty (~> 0.14)
@@ -133,7 +133,7 @@ GEM
       activerecord
       kaminari-core (= 1.1.1)
     kaminari-core (1.1.1)
-    loofah (2.2.3)
+    loofah (2.3.1)
       crass (~> 1.0.2)
       nokogiri (>= 1.5.9)
     marcel (0.3.3)
@@ -157,7 +157,7 @@ GEM
       activerecord (>= 3.0.0)
       activesupport (>= 3.0.0)
     nio4r (2.3.1)
-    nokogiri (1.10.1)
+    nokogiri (1.10.5)
       mini_portile2 (~> 2.4.0)
     puma (3.12.0)
     rack (2.0.6)