build(npm): ⬇️ mocha

build breaks on node 6 due to mochajs/mocha#3866

using 6.0.2 until that is fixed, or node 6 is de-supported whichever comes first

package.json

@@ -91,7 +91,8 @@
   },
   "upem": {
     "donotup": [
-      "symlink-dir"
+      "symlink-dir",
+      "mocha"
     ]
   },
   "dependencies": {
@@ -125,7 +126,7 @@
     "eslint-plugin-node": "8.0.1",
     "eslint-plugin-security": "1.4.0",
     "intercept-stdout": "0.1.2",
-    "mocha": "6.1.0",
+    "mocha": "6.0.2",
     "normalize-newline": "3.0.0",
     "npm-run-all": "4.1.5",
     "nyc": "13.3.0",