fix(ci): drop php 8.4, deps don't support it

Author: ivuorinen

.github/workflows/phpunit.yml

@@ -19,7 +19,7 @@ jobs:
     strategy:
       fail-fast: true
       matrix:
-        php: [ '8.0', '8.1', '8.2', '8.3', '8.4' ]
+        php: [ '8.0', '8.1', '8.2', '8.3' ]
 
     steps:
       - uses: actions/checkout@v4

composer.json

@@ -21,7 +21,7 @@
         "php": "^8.0"
     },
     "require-dev": {
-        "orchestra/testbench": "^7",
+        "orchestra/testbench": "^7|^8",
         "rector/rector": "^1",
         "ergebnis/composer-normalize": "^2",
         "vimeo/psalm": "^5",