ci: configure travis ci job builds

Author: Harrison Ifeanyichukwu

.travis.yml

@@ -9,9 +9,13 @@ script:
 jobs:
   include:
     - stage: release
-      php: "7.2"
+      php: 7.2
+      before_install:
+        - nvm install 10
       before_script:
         - composer self-update
         - composer install
       script:
         - vendor/bin/phpunit
+      after_success:
+        - php vendor/bin/php-coveralls