Downgrade Halite to v4 to support PHP v7

Author: birdcar

composer.json

@@ -12,7 +12,7 @@
   "require": {
     "php": ">=7.3.0",
     "ext-curl": "*",
-    "paragonie/halite": "^5.0"
+    "paragonie/halite": "^4.0"
   },
   "require-dev": {
     "friendsofphp/php-cs-fixer": "^2.15|^3.6",