Update minimum PHP version to 7.1 in Travis

.travis.yml

@@ -18,7 +18,7 @@ addons:
 env:
   global:
     - TRAVIS_NODE_VERSION="10"
-    - COMPOSER_ROOT_VERSION="4.4.x-dev"
+    - COMPOSER_ROOT_VERSION="4.5.x-dev"
     - DISPLAY=":99"
     - XVFBARGS=":99 -ac -screen 0 1024x768x16"
     - SS_BASE_URL="http://localhost:8080/"
@@ -27,13 +27,13 @@ env:
 matrix:
   fast_finish: true
   include:
-    - php: 5.6
-      env: DB=MYSQL PHPUNIT_TEST=1 PHPCS_TEST=1
-    - php: 7.0
-      env: DB=PGSQL PHPUNIT_TEST=1
     - php: 7.1
-      env: DB=MYSQL PDO=1 PHPUNIT_TEST=1
+      env: DB=MYSQL PHPUNIT_TEST=1 PHPCS_TEST=1
     - php: 7.2
+      env: DB=PGSQL PHPUNIT_TEST=1
+    - php: 7.3
+      env: DB=MYSQL PDO=1 PHPUNIT_TEST=1
+    - php: 7.1
       env: DB=MYSQL BEHAT_TEST=1
     - php: 7.2
       env: NPM_TEST=1
@@ -52,7 +52,7 @@ before_script:
 
 # Install composer dependencies
   - composer validate
-  - composer require --no-update silverstripe/recipe-testing:^1 silverstripe/recipe-cms:4.4.x-dev
+  - composer require --no-update silverstripe/recipe-testing:^1 silverstripe/recipe-cms:4.5.x-dev
   - if [[ $DB == PGSQL ]]; then composer require --no-update silverstripe/postgresql:2.1.x-dev; fi
   - composer install --prefer-source --no-interaction --no-progress --no-suggest --optimize-autoloader --verbose --profile