fix travis

.travis.yml

@@ -4,12 +4,14 @@ addons:
   apt:
     packages:
       - libgirepository1.0-dev # for gobject-introspection
-      - ruby-pango
 rvm:
   - 2.4.2
   - 2.5.3
   - 2.6.3
   - ruby-head
+before_install:
+  - gem update --system
+  - gem install bundler
 matrix:
   allow_failures:
     - rvm: ruby-head