chore: move polished to dependencies from devDependensies

Author: morajabi

packages/graphql-playground/package.json

@@ -72,7 +72,6 @@
     "lint-staged": "^4.0.2",
     "node-noop": "^1.0.0",
     "object-assign": "4.1.0",
-    "polished": "^1.9.0",
     "postcss-cssnext": "^2.9.0",
     "postcss-flexbugs-fixes": "^3.2.0",
     "postcss-import": "^9.1.0",
@@ -120,6 +119,7 @@
     "graphql": "^0.10.5",
     "isomorphic-fetch": "^2.2.1",
     "js-yaml": "^3.10.0",
+    "polished": "^1.9.0",
     "json-stable-stringify": "^1.0.1",
     "keycode": "^2.1.9",
     "lodash": "^4.17.4",