Remove 'bourbon' dependency. It's been replaced with automated prefixing tool.

assets/css/activation.scss

@@ -3,11 +3,6 @@
  * Styles applied to elements displayed on activation
  */
 
-/**
- * Imports
- */
-@import 'bourbon';
-
 /**
  * Styling begins
  */

assets/css/admin.scss

@@ -7,7 +7,6 @@
 /**
  * Imports
  */
-@import 'bourbon';
 @import 'mixins';
 @import 'variables';
 @import 'animation';

assets/css/dashboard.scss

@@ -6,7 +6,6 @@
 /**
  * Imports
  */
-@import 'bourbon';
 @import 'mixins';
 @import 'variables';
 @import 'fonts';

assets/css/menu.scss

@@ -7,7 +7,6 @@
 /**
  * Imports
  */
-@import 'bourbon';
 @import 'mixins';
 @import 'variables';
 @import 'fonts';

assets/css/prettyPhoto.scss

@@ -7,7 +7,6 @@
 /**
  * Imports
  */
-@import 'bourbon';
 @import 'mixins';
 @import 'variables';
 @import 'fonts';

assets/css/twenty-seventeen.scss

@@ -2,8 +2,6 @@
  * Twenty Seventeen integration styles
  */
 
-@import 'bourbon';
-
 /**
  * Fonts
  */

assets/css/woocommerce-layout.scss

@@ -6,7 +6,6 @@
 /**
  * Imports
  */
-@import 'bourbon';
 @import 'mixins';
 @import 'variables';
 

assets/css/woocommerce-smallscreen.scss

@@ -6,7 +6,6 @@
 /**
  * Imports
  */
-@import 'bourbon';
 @import 'mixins';
 @import 'variables';
 

assets/css/woocommerce.scss

@@ -7,7 +7,6 @@
 /**
  * Imports
  */
-@import 'bourbon';
 @import 'mixins';
 @import 'variables';
 @import 'animation';

package.json

@@ -43,7 +43,6 @@
     "grunt-wp-i18n": "~0.5.4",
     "istanbul": "^1.0.0-alpha",
     "mocha": "^3.0.2",
-    "node-bourbon": "~4.2.3",
     "wc-e2e-page-objects": "0.2.2"
   },
   "engines": {