.travis.yml in ffi-wiring_pi-0.2.0 vs .travis.yml in ffi-wiring_pi-0.3.0

@@ -2,8 +2,9 @@
 before_install:
   - git clone git://git.drogon.net/wiringPi
   - cd wiringPi
   - ./build
   - gem install ffi
+  - gem install bundler:2.0.1
 rvm:
   - 2.6.1
 script: rake test