.travis.yml in awsecrets-1.14.0 vs .travis.yml in awsecrets-1.15.0

@@ -1,11 +1,22 @@
+---
 language: ruby
-rvm:
-  - 2.3.4
-  - 2.2.7
-
+matrix:
+  include:
+    - rvm: 2.6.2
+      env: RUBYGEMS_VERSION=
+    - rvm: 2.5.3
+      env: RUBYGEMS_VERSION=
+    - rvm: 2.4.5
+      env: RUBYGEMS_VERSION=
+    - rvm: 2.3.8
+      env: RUBYGEMS_VERSION=
+    - rvm: 2.2.10
+      env: RUBYGEMS_VERSION=2.7.8
+    - rvm: 2.1.10
+      env: RUBYGEMS_VERSION=2.7.8
 before_install:
-  - gem update bundler
-  
+  - gem update --system ${RUBYGEMS_VERSION}
+  - gem pristine bundler
+
 script:
   - bundle exec rake spec
-