build(deps-dev): Bump web-ext from 3.2.0 to 3.2.1 in /addon

Bumps [web-ext](https://github.com/mozilla/web-ext) from 3.2.0 to 3.2.1.
- [Release notes](https://github.com/mozilla/web-ext/releases)
- [Commits](mozilla/web-ext@3.2.0...3.2.1)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Author: dependabot-preview[bot]

addon/package-lock.json

@@ -11,7 +11,7 @@
   "devDependencies": {
     "eslint-plugin-mozilla": "^0.9.0",
     "eslint-plugin-no-unsanitized": "^3.0.2",
-    "web-ext": "^3.2.0",
+    "web-ext": "^3.2.1",
     "webpack": "^4.41.2",
     "webpack-cli": "^3.3.10"
   },