Bump axios from 0.20.0 to 0.21.1 in /pusher

Bumps [axios](https://github.com/axios/axios) from 0.20.0 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](https://github.com/axios/axios/compare/v0.20.0...v0.21.1)

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

pusher/package.json

@@ -37,7 +37,7 @@
   },
   "homepage": "https://github.com/thecodingmachine/workadventure#readme",
   "dependencies": {
-    "axios": "^0.20.0",
+    "axios": "^0.21.1",
     "body-parser": "^1.19.0",
     "busboy": "^0.3.1",
     "circular-json": "^0.5.9",