Remove unused proper-skip-list dependency

client/package.json

@@ -59,7 +59,6 @@
     "object-hash": "^2.2.0",
     "popper.js": "^1.16.1",
     "pretty-bytes": "^5.6.0",
-    "proper-skip-list": "^4.1.0",
     "pyre-to-regexp": "^0.0.5",
     "querystring-es3": "^0.2.1",
     "regenerator-runtime": "^0.13.9",

client/yarn.lock

@@ -7920,11 +7920,6 @@ proper-lockfile@^2.0.1:
     graceful-fs "^4.1.2"
     retry "^0.10.0"
 
-proper-skip-list@^4.1.0:
-  version "4.1.0"
-  resolved "https://registry.yarnpkg.com/proper-skip-list/-/proper-skip-list-4.1.0.tgz#d23bbb844591e1e05ee66b910a740c595248da79"
-  integrity sha512-NrucFFMTdbNNe9XHZcYLBIg3mQPqXq25scUJMr3szG7MIdXyQigby2ATLvrNJdYaVI9CJbpiOA3qckhXZ2MuGQ==
-
 proto-list@~1.2.1:
   version "1.2.4"
   resolved "https://registry.yarnpkg.com/proto-list/-/proto-list-1.2.4.tgz#212d5bfe1318306a420f6402b8e26ff39647a849"