update ruby version in travis config

lostapathy · lostapathy · commit cb3bb7dbd968 · 2017-10-07T13:31:44.000-05:00
diff --git a/.travis.yml b/.travis.yml
@@ -8,9 +8,9 @@ rvm:
   - 1.9.3
   - 2.0.0
   - 2.1.10
-  - 2.2.7
-  - 2.3.4
-  - 2.4.1
+  - 2.2.8
+  - 2.3.5
+  - 2.4.2
   - ruby-head
 matrix:
   allow_failures:
