Declare ext-json dependency

Author: e1himself

composer.json

@@ -8,7 +8,8 @@
         "minimalist"
     ],
     "require": {
-        "php": "~7.3 || ~8.0"
+        "php": "~7.3 || ~8.0",
+        "ext-json": "*"
     },
     "require-dev": {
         "peridot-php/peridot": "^1.19"