Downgraded mocha and eslint

- unfortunately `mocha` v9 and `eslint` v7 drop support for Node 10 and
  11, but I don't want to start introducing Node version drops if I can
  avoid it
- downgrading them fixes the problem in the mean time

package.json

@@ -46,8 +46,8 @@
     "tar": "^6.1.11"
   },
   "devDependencies": {
-    "eslint": "^7.32.0",
-    "mocha": "^9.2.2"
+    "eslint": "^6.8.0",
+    "mocha": "^7.2.0"
   },
   "peerDependencies": {
     "node-gyp": "8.x"