BUG Fix Travis build config

.travis.yml

@@ -1,6 +1,6 @@
 language: php
 
-dist: precise
+dist: xenial
 
 sudo: false
 
@@ -29,7 +29,7 @@ before_script:
   - export PATH=~/.composer/vendor/bin:$PATH
   - composer validate
   - composer install --dev --prefer-dist
-  - composer require --prefer-dist --no-update silverstripe/recipe-core:1.0.x-dev
+  - composer require --prefer-dist --no-update silverstripe/recipe-core:^4
   - composer update
   - if [[ $PHPCS_TEST ]]; then composer global require squizlabs/php_codesniffer:^3 --prefer-dist --no-interaction --no-progress --no-suggest -o; fi
   - phpenv rehash