Travis config update

.travis.yml

@@ -1,25 +1,35 @@
 language: php
 
+dist: xenial
+
+services:
+  - mysql
+  - postgresql
+
+env:
+  global:
+    - COMPOSER_ROOT_VERSION="3.x-dev"
+
 matrix:
   include:
     - php: 5.6
-      env: DB=MYSQL RECIPE_VERSION=1.0.x-dev PHPCS_TEST=1 PHPUNIT_TEST=1
+      env: DB=MYSQL PHPUNIT_TEST=1 RECIPE_VERSION="^1 --prefer-lowest"
     - php: 7.0
-      env: DB=MYSQL RECIPE_VERSION=1.1.x-dev PHPUNIT_TEST=1
+      env: DB=MYSQL PHPUNIT_TEST=1 RECIPE_VERSION="^1"
     - php: 7.1
-      env: DB=PGSQL RECIPE_VERSION=4.2.x-dev PHPUNIT_COVERAGE_TEST=1
+      env: DB=PGSQL PHPUNIT_TEST=1 RECIPE_VERSION="^4 --prefer-lowest"
     - php: 7.2
-      env: DB=MYSQL RECIPE_VERSION=4.3.x-dev PHPUNIT_TEST=1
+      env: DB=MYSQL PHPUNIT_TEST=1 PHPCS_TEST=1 RECIPE_VERSION="^4"
     - php: 7.3
-      env: DB=MYSQL RECIPE_VERSION=4.x-dev PHPUNIT_TEST=1
+      env: DB=MYSQL PHPUNIT_COVERAGE_TEST=1 RECIPE_VERSION="4.x-dev"
 
 before_script:
   - phpenv rehash
   - phpenv config-rm xdebug.ini
 
   - composer validate
-  - composer require silverstripe/recipe-cms:"$RECIPE_VERSION"  --no-update
-  - if [[ $DB == PGSQL ]]; then composer require silverstripe/postgresql:2.1.x-dev --no-update; fi
+  - composer require silverstripe/recipe-cms:$RECIPE_VERSION --no-update
+  - if [[ $DB == PGSQL ]]; then composer require silverstripe/postgresql:^2 --no-update; fi
   - composer install --prefer-dist --no-interaction --no-progress --no-suggest --optimize-autoloader --verbose --profile
 
 script: