remove dep on rescript core for v12

Author: jfrolich

rewatch/testrepo/packages/with-dev-deps/package.json

@@ -5,8 +5,5 @@
     "rescript"
   ],
   "author": "",
-  "license": "MIT",
-  "dependencies": {
-    "@rescript/core": "*"
-  }
+  "license": "MIT"
 }

rewatch/testrepo/packages/with-dev-deps/rescript.json

@@ -13,6 +13,5 @@
     "module": "es6",
     "in-source": true
   },
-  "bs-dependencies": ["@rescript/core"],
   "suffix": ".res.js"
 }