Allow PHP 8

We want to allow our users to experiment and report bugs if there are
any.

Author: greg0ire

.travis.yml

@@ -6,7 +6,6 @@ php:
   - 7.2
   - 7.3
   - 7.4
-  - nightly
 
 cache:
   directories:
@@ -32,6 +31,11 @@ jobs:
     - php: nightly
 
   include:
+    - stage: Test
+      php: nightly
+      before_install:
+        - composer config platform.php 7.4.99
+
     - stage: Validate against schema
       addons:
         apt:

composer.json

@@ -21,7 +21,7 @@
         {"name": "Steve Müller", "email": "[email protected]"}
     ],
     "require": {
-        "php": "^7.2",
+        "php": "^7.2 || ^8.0",
         "dealerdirect/phpcodesniffer-composer-installer": "^0.6.2",
         "slevomat/coding-standard": "^6.2.0",
         "squizlabs/php_codesniffer": "^3.5.4"