update version of ruby used for 2.3.x

JonRowe · JonRowe · commit fa0201959350 · 2017-01-30T20:45:17.000+11:00
diff --git a/.travis.yml b/.travis.yml
@@ -34,7 +34,7 @@ script: "script/run_build 2>&1"
 rvm:
   - 1.8.7
   - 2.4.0
-  - 2.3.1
+  - 2.3.3
   - 2.2
   - 2.1
   - 2.0.0

-Original file line number
+Diff line change
 rvm:
   - 1.8.7
   - 2.4.0
 -  - 2.3.1
 +  - 2.3.3
   - 2.2
   - 2.1
   - 2.0.0