fix: Change /core to devDep and change import for Theme interface

Author: LekoArts

packages/custom-properties/package.json

@@ -16,10 +16,10 @@
     "access": "public"
   },
   "dependencies": {
-    "@theme-ui/core": "^0.3.1",
     "pluralize": "^8.0.0"
   },
   "devDependencies": {
+    "@theme-ui/core": "^0.3.1",
     "@types/pluralize": "^0.0.29"
   }
 }

packages/custom-properties/src/index.ts

@@ -1,5 +1,5 @@
 import pluralize from 'pluralize'
-import { Theme } from '@theme-ui/core/dist/theme'
+import { Theme } from '@theme-ui/core'
 
 interface CustomProperties {
   [key: string]: string | number