fix(deps): update dependency php to v8

Author: renovate-bot

bookshelf/composer.json

@@ -1,6 +1,6 @@
 {
   "require": {
-    "php": "^7.1.3",
+    "php": "^8.0.0",
     "laravel/lumen-framework": "5.8.*",
     "google/cloud-storage": "^1.11",
     "google/cloud-firestore": "^1.2",