Dockerfile in arstotzka-1.5.0 vs Dockerfile in arstotzka-1.6.0

@@ -1,5 +1,5 @@
-FROM darthjee/rails_gems:0.5.3 as base
+FROM darthjee/ruby_gems:0.5.4 as base
 FROM darthjee/scripts:0.1.8 as scripts
 
 ######################################
 
 FROM base as builder