Add support for composer installer 2.0

Author: spacedmonkey

composer.json

@@ -25,7 +25,7 @@
     },
     "require": {
       "php": "^5.4 || ^7.0 || ^8.0",
-      "composer/installers": "~1.0"
+      "composer/installers": "^1.0 || ^2.0"
     },
     "require-dev": {
         "wp-coding-standards/wpcs": "^3.0",