fix rbx version for travis?

ioquatix · ioquatix · commit 1b8bd41b9f83 · 2017-03-09T23:37:38.000+13:00
diff --git a/.travis.yml b/.travis.yml
@@ -17,14 +17,14 @@ rvm:
   - 2.2.4
   - 2.3.2
   - 2.4.0
-  - rbx
+  - rbx-3.72
   - jruby-9.0.5.0
   - jruby-9.1.5.0
   - jruby-head
 
 matrix:
   allow_failures:
-    - rvm: rbx
+    - rvm: rbx-3.72
 
 cache: bundler
 
