.travis.yml in imap-backup-2.0.0.rc1 vs .travis.yml in imap-backup-2.0.0.rc2

@@ -1,11 +1,9 @@
 language: ruby
 rvm:
-  - 2.1.10
-  - 2.2.10
-  - 2.3.7
-  - 2.4.4
-  - 2.5.1
+  - 2.3
+  - 2.4
+  - 2.5
 branches:
   only:
     - master
 before_install:
   - gem update --system