add support for Backpack v7 (#366)

Co-authored-by: pxpm <[email protected]>

Author: tabacitu

composer.json

@@ -34,7 +34,7 @@
     "prefer-stable": true,
     "require": {
         "spatie/laravel-permission": "^6.4||^5.0||^4.0||^3.0",
-        "backpack/crud": "^6.0"
+        "backpack/crud": "^6.0||^7.0"
     },
     "autoload": {
         "psr-4": {