use correct composer package.

.travis.yml

@@ -16,7 +16,6 @@ cache:
 
 php:
  - 5.6
- - 7.0
  - 7.1
 
 env:
@@ -31,7 +30,7 @@ before_install:
   - nvm install node
   - cd ../..
   - composer selfupdate
-  - composer create-project -n --no-dev --prefer-dist moodlerooms/moodle-plugin-ci ci v2.x-dev
+  - composer create-project -n --no-dev --prefer-dist moodlerooms/moodle-plugin-ci ci ^2
   - export PATH="$(cd ci/bin; pwd):$(cd ci/vendor/bin; pwd):$PATH"
 
 install: