Add php 8 to packages' build matrices; normalize composer reqs

Author: andrewmy

.github/workflows/ci.yml

@@ -10,7 +10,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        php: ['7.3', '7.4']
+        php: ['7.3', '7.4', '8.0']
 
     name: PHP ${{ matrix.php }} tests
 

composer.json

@@ -6,10 +6,10 @@
     "homepage": "https://enqueue.forma-pro.com/",
     "license": "MIT",
     "require": {
-        "php": "^7.1.3"
+        "php": "^7.3|^8.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "~7.5"
+        "phpunit/phpunit": "^9.5"
     },
     "support": {
         "email": "opensource@forma-pro.com",