Composer 2 (#398)

* Remove rvtraveller/qs-composer-installer and update other dependency versions for Compsoer 2 compatibility.

* Allow php 7.3 and update again.

Author: greg-1-anderson

composer.json

@@ -14,12 +14,11 @@
     }
   ],
   "require": {
-    "php": ">=7.2",
+    "php": ">=7.3",
     "composer/installers": "^1.3.0",
     "pantheon-systems/quicksilver-pushback": "^2",
     "pantheon-systems/wordpress-composer": "*",
     "roots/wp-password-bcrypt": "^1.0.0",
-    "rvtraveller/qs-composer-installer": "^1.1",
     "vlucas/phpdotenv": "^3.1.0",
     "wpackagist-plugin/lh-hsts": "^1.24",
     "wpackagist-plugin/pantheon-advanced-page-cache": ">=0.3.0",
@@ -29,7 +28,7 @@
   "require-dev": {
     "behat/mink-goutte-driver": "^1.2.1",
     "brain/monkey": "^2.2.0",
-    "dealerdirect/phpcodesniffer-composer-installer": "^0.5.0",
+    "dealerdirect/phpcodesniffer-composer-installer": "^0.7",
     "dmore/behat-chrome-extension": "^1.2",
     "genesis/behat-fail-aid": "^2.1",
     "paulgibbs/behat-wordpress-extension": "^3.3.0",
@@ -44,7 +43,7 @@
     "optimize-autoloader": true,
     "sort-packages": true,
     "platform": {
-      "php": "7.2"
+      "php": "7.3"
     }
   },
   "extra": {