Fix doctor warning and animation

Summary: Two random tiny changes

Reviewed By: nikoant

Differential Revision: D19309447

fbshipit-source-id: 13a1a66d6b91285a00177ca7a3003fd83b4820f5

src/reducers/healthchecks.tsx

@@ -8,7 +8,7 @@
  */
 
 import {Actions} from './';
-import {produce} from 'flipper';
+import {produce} from 'immer';
 import {Healthchecks} from 'flipper-doctor';
 
 export type State = {