chore(ci): add 2.7, ruby-head and jruby-head (jjbohn#55)

bufferoverflow · web-flow · commit 48d76795f431 · 2020-05-21T09:38:10.000+02:00
diff --git a/.travis.yml b/.travis.yml
@@ -3,3 +3,6 @@ rvm:
   - 2.4
   - 2.5
   - 2.6
+  - 2.7
+  - jruby-head
+  - ruby-head
