Move icon build tools to dev dep in express icons (#3768)

Author: devongovett

packages/@spectrum-icons/express/package.json

@@ -14,8 +14,7 @@
   "dependencies": {
     "@adobe/spectrum-css-ccx-workflow-icons": "1.0.2",
     "@babel/runtime": "^7.6.2",
-    "@react-spectrum/icon": "^3.6.2",
-    "@spectrum-icons/build-tools": "3.0.0-alpha.1"
+    "@react-spectrum/icon": "^3.6.2"
   },
   "devDependencies": {
     "@spectrum-icons/build-tools": "3.0.0-alpha.1",