Remove ws dependency

Summary: Is it too early for spring cleaning? We don't use websockets anymore, do we? Couldn't find any imports or `require()`s.

Reviewed By: jknoxville

Differential Revision: D12997868

fbshipit-source-id: c87c67ec98b925c4209b97bf00e91fce67215465

package.json

@@ -87,7 +87,6 @@
     "string-natural-compare": "^2.0.2",
     "tmp": "^0.0.33",
     "websocket": "^1.0.24",
-    "ws": "^4.0.0",
     "xml2js": "^0.4.19",
     "yargs": "^11.0.0"
   },

yarn.lock

@@ -6704,13 +6704,6 @@ ws@^2.0.3:
     safe-buffer "~5.0.1"
     ultron "~1.1.0"
 
-ws@^4.0.0:
-  version "4.1.0"
-  resolved "https://registry.yarnpkg.com/ws/-/ws-4.1.0.tgz#a979b5d7d4da68bf54efe0408967c324869a7289"
-  dependencies:
-    async-limiter "~1.0.0"
-    safe-buffer "~5.1.0"
-
 ws@^5.2.0:
   version "5.2.2"
   resolved "https://registry.yarnpkg.com/ws/-/ws-5.2.2.tgz#dffef14866b8e8dc9133582514d1befaf96e980f"