.travis.yml in ztimer-0.5.0 vs .travis.yml in ztimer-0.6.0

@@ -1,4 +1,9 @@
 language: ruby
 rvm:
-  - 2.2.1
+  - 2.2
+
 before_install: gem install bundler -v 1.11.2
+script:
+  - gem build ztimer.gemspec
+  - gem install ztimer --local
+  - bundle exec rspec