update js-client-sdk to 2.20.2 for sc-142333 fix (#53)

Author: eli-darkly

package.json

@@ -67,7 +67,7 @@
   },
   "dependencies": {
     "hoist-non-react-statics": "^3.3.2",
-    "launchdarkly-js-client-sdk": "2.20.1",
+    "launchdarkly-js-client-sdk": "2.20.2",
     "lodash.camelcase": "^4.3.0",
     "uuid": "^3.3.2"
   },