Run code style and coverage with PHP 7.4

.travis.yml

@@ -24,13 +24,13 @@ jobs:
   include:
 
     - stage: Code style
-      php: 7.2
+      php: 7.4
       script:
         - ./vendor/bin/php-cs-fixer fix --diff --verbose --dry-run
         - ./vendor/bin/phpcs --report-width=200 samples/ src/ tests/ --ignore=samples/Header.php --standard=PSR2 -n
 
     - stage: Coverage
-      php: 7.2
+      php: 7.4
       script:
         - pecl install pcov
         - composer require pcov/clobber --dev