Update .travis.yml

Author: joppuyo

.travis.yml

@@ -4,7 +4,7 @@ php:
 before_script:
   - sudo add-apt-repository -y ppa:dhor/myway
   - sudo apt-get update
-  - sudo apt-get install -y vips
+  - sudo apt-get install -y libvips-dev
   - yes | pecl install vips
   - echo "extension=vips.so" >> ~/.phpenv/versions/$(phpenv version-name)/etc/php.ini
 script: