Add PHP8 support

Author: dmitry-ivanov

Diff for: .travis.yml

@@ -4,6 +4,12 @@ php:
   - 7.2
   - 7.3
   - 7.4
+  - 8.0
+
+env:
+  global:
+    - COMPOSER_MEMORY_LIMIT=-1
+    - XDEBUG_MODE=coverage
 
 cache:
   directories:
@@ -13,8 +19,8 @@ services:
   - mysql
 
 install:
-  - COMPOSER_MEMORY_LIMIT=-1 travis_retry composer install --no-interaction --prefer-dist
-  - COMPOSER_MEMORY_LIMIT=-1 travis_retry composer require --no-interaction --prefer-dist --dev php-coveralls/php-coveralls
+  - travis_retry composer install --no-interaction --prefer-dist
+  - travis_retry composer require --no-interaction --prefer-dist --dev php-coveralls/php-coveralls
 
 script: vendor/bin/phpunit --verbose --coverage-clover build/logs/clover.xml
 

Diff for: composer.json

@@ -12,7 +12,7 @@
         "email": "[email protected]"
     }],
     "require": {
-        "php": "^7.2.5",
+        "php": "^7.2.5|^8.0",
         "ext-json": "*",
         "illuminate/support": "^7.0",
         "illuminate/console": "^7.0",