.travis.yml in tdlib-ruby-2.0.0 vs .travis.yml in tdlib-ruby-2.1.0

@@ -1,8 +1,8 @@
 language: ruby
 rvm:
-- 2.3.8
-- 2.6.0
+- 2.4.9
+- 2.6.5
 addons:
   apt:
     sources:
     - ubuntu-toolchain-r-test
     - llvm-toolchain-precise-3.8