Update to @emotion 11

packages/netlify-cms-ui-default/package.json

@@ -22,8 +22,8 @@
     "react-transition-group": "^4.0.0"
   },
   "peerDependencies": {
-    "@emotion/core": "^10.0.35",
-    "@emotion/styled": "^10.0.27",
+    "@emotion/core": "11.0.0",
+    "@emotion/styled": "11.10.4",
     "lodash": "^4.17.11",
     "prop-types": "^15.7.2",
     "react": "^16.8.4 || ^17.0.0"