Upgrade: Bump immer from 7.0.5 to 9.0.6 in /ch6/front

Bumps [immer](https://github.com/immerjs/immer) from 7.0.5 to 9.0.6.
- [Release notes](https://github.com/immerjs/immer/releases)
- [Commits](immerjs/immer@v7.0.5...v9.0.6)

---
updated-dependencies:
- dependency-name: immer
  dependency-type: direct:production
...

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

Author: dependabot[bot]

ch6/front/package-lock.json

@@ -18,7 +18,7 @@
     "cookie-parser": "^1.4.5",
     "cross-env": "^7.0.2",
     "dotenv": "^8.2.0",
-    "immer": "^7.0.5",
+    "immer": "^9.0.6",
     "moment": "^2.27.0",
     "next": "^9.4.4",
     "next-redux-saga": "^4.1.2",