Update .travis.yml

Author: Torann

.travis.yml

@@ -4,11 +4,12 @@ php:
   - 7.2
   - 7.3
   - 7.4
+  - 8.0
 
 before_script:
   - curl -s http://getcomposer.org/installer | php
   - php composer.phar install
 
 script:
   - ./vendor/bin/phpcs --standard=phpcs.xml src
-  - ./vendor/bin/phpstan --level=0 --memory-limit=-1 --no-progress analyse src
+  - ./vendor/bin/phpstan --level=0 --memory-limit=-1 --no-progress analyse src