chore: remove @aws-sdk/util-utf8-universal (#368)

It was not being used,
and was getting deprecated.

aws/aws-sdk-js-v3#1241
aws/aws-sdk-js-v3#1240?

Author: seebees

package-lock.json

@@ -93,7 +93,6 @@
   "devDependencies": {
     "@aws-sdk/credential-provider-node": "^1.0.0-alpha.7",
     "@aws-sdk/karma-credential-loader": "^1.0.0-alpha.6",
-    "@aws-sdk/util-utf8-universal": "^1.0.0-alpha.3",
     "@types/bn.js": "^4.11.0",
     "@types/chai": "^4.2.11",
     "@types/chai-as-promised": "^7.1.0",