Update travis.yml.

.travis.yml

@@ -1,37 +1,35 @@
 language: php
 sudo: false
 dist: trusty
+branches:
+  only:
+  - dev
+  - "/\\d+\\.\\d+(\\.\\d+)?(-\\S*)?$/"
 php:
   - 7.1
   - 7.0
   - nightly
-
 env:
   - TRAVIS_NODE_VERSION="6"
   - TRAVIS_NODE_VERSION="7"
-
 matrix:
   fast_finish: true
   allow_failures:
     - php: nightly
-
 cache:
   apt: true
   directories:
     - $HOME/.composer/cache
     - $HOME/.yarn-cache
     - vendor
-
 before_install:
   - composer self-update
   - source ~/.nvm/nvm.sh && nvm install $TRAVIS_NODE_VERSION && nvm use $TRAVIS_NODE_VERSION
   - export PATH=$HOME/.yarn/bin:$PATH && travis_retry curl -o- -L https://yarnpkg.com/install.sh | bash
-
 install:
   - node -v && yarn -V
   - travis_retry yarn
   - composer install -o --prefer-dist --no-interaction
-
 script:
   - yarn run test
   - yarn run build