Update travis

Author: wilr

.travis.yml

@@ -10,7 +10,7 @@ matrix:
   include:
     - php: 7.1
       env: DB=MYSQL PHPUNIT_TEST=1
-    - php: 7.2
+    - php: 7.3
       env: DB=MYSQL PHPUNIT_TEST=1
 
 before_script:
@@ -20,8 +20,7 @@ before_script:
 
   # Install composer dependencies
   - composer validate
-  - composer require --no-update silverstripe/recipe-core:1.0.x-dev
-  - if [[ $DB == PGSQL ]]; then composer require --no-update silverstripe/postgresql:2.0.x-dev; fi
+  - composer require --no-update silverstripe/recipe-core:4.5.x-dev
   - composer install --prefer-dist --no-interaction --no-progress --no-suggest --optimize-autoloader --verbose --profile
 
 script: