.travis.yml in cqm-validators-2.0.2 vs .travis.yml in cqm-validators-3.0.0

@@ -1,8 +1,10 @@
 language: ruby
 rvm:
   - 2.6
   - 2.5
+  - 2.4
+  - 2.3
 cache:
   - bundler
 sudo: required
 services:
   - mongodb