Update phpunit to 8.5

Author: VicDeo

.travis.yml

@@ -1,8 +1,8 @@
 sudo: false
 language: php
 php:
-  - 7.1
   - 7.2
+  - 7.3
 
 install:
   - sh -c "cd update-server/ && composer install"

update-server/composer.json

@@ -12,6 +12,8 @@
   },
   "require-dev": {
     "behat/behat": "~3.4.3",
-    "phpunit/phpunit": "^7"
+    "phpunit/phpunit": "^8",
+    "phpunit/php-code-coverage": "^7.0",
+    "sebastian/global-state": "^3.0"
   }
 }