Bump axios from 0.18.0 to 0.21.1 in /web-ext

Bumps [axios](https://github.com/axios/axios) from 0.18.0 to 0.21.1.
- [Release notes](https://github.com/axios/axios/releases)
- [Changelog](https://github.com/axios/axios/blob/v0.21.1/CHANGELOG.md)
- [Commits](axios/axios@v0.18.0...v0.21.1)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

web-ext/package-lock.json

@@ -11,7 +11,7 @@
     "author": "",
     "license": "ISC",
     "dependencies": {
-        "axios": "^0.18.0",
+        "axios": "^0.21.1",
         "jquery": "^3.3.1",
         "webextension-polyfill": "^0.2.1"
     },