Require phpcompatibility/php-compatibility

instead of wimg/php-compatibility.

See #22

Author: gmazzap

composer.json

@@ -32,7 +32,7 @@
     "dealerdirect/phpcodesniffer-composer-installer": "^0.4",
     "wp-coding-standards/wpcs": "^0.14",
     "automattic/phpcs-neutron-standard": "^1",
-    "wimg/php-compatibility": "^8.0"
+    "phpcompatibility/php-compatibility": "^9.0"
   },
   "require-dev": {
     "phpunit/phpunit": "6.0.*"