fix(deps): update dependency yargs to v15 (#469)

Author: renovate-bot

speech/package.json

@@ -16,7 +16,7 @@
     "chalk": "^3.0.0",
     "node-record-lpcm16": "^1.0.1",
     "sox": "^0.1.0",
-    "yargs": "^14.0.0"
+    "yargs": "^15.0.0"
   },
   "devDependencies": {
     "chai": "^4.2.0",