Updated mocha dependency to v9

- this fixes the last remaining security advisory against the repo
- `devDependencies` should probably be pinned - will come in a future
  commit

Author: daniellockyer

package.json

@@ -47,7 +47,7 @@
     "@mapbox/cloudfriend": "^1.9.0",
     "aws-sdk": "2.x",
     "eslint": "^7.32.0",
-    "mocha": "^5.2.0"
+    "mocha": "^9.2.2"
   },
   "peerDependencies": {
     "node-gyp": "7.x"