update dev environment

* remove remaining Robo calls from Composer scripts
* update WP test bootstrap
* update dev dependencies

composer.json

@@ -18,16 +18,16 @@
   "type": "wordpress-plugin",
   "require": {
     "php": ">=5.6",
-    "composer/installers": "~1.7"
+    "composer/installers": "~1.12"
   },
   "require-dev": {
-    "phpunit/phpunit": "^5|^6|^7",
     "dealerdirect/phpcodesniffer-composer-installer": "^0.7",
+    "matthiasmullie/minify": "^1.3",
+    "phpcompatibility/phpcompatibility-wp": "^2.1",
+    "phpunit/phpunit": "^5|^6|^7",
     "slowprog/composer-copy-file": "~0.3",
     "squizlabs/php_codesniffer": "^3.6",
-    "phpcompatibility/phpcompatibility-wp": "^2.1",
     "wp-coding-standards/wpcs": "^2.3",
-    "matthiasmullie/minify": "^1.3",
     "yoast/phpunit-polyfills": "^1.0"
   },
   "scripts": {
@@ -38,16 +38,7 @@
       "@minify"
     ],
     "build": [
-      "@minify",
-      "robo build"
-    ],
-    "package": [
-      "@minify",
-      "robo package"
-    ],
-    "deploy": [
-      "@minify",
-      "robo deploy:all"
+      "@minify"
     ],
     "test": [
       "phpunit"