Bump minimist from 1.2.5 to 1.2.6 in /backend

Bumps [minimist](https://github.com/substack/minimist) from 1.2.5 to 1.2.6.
- [Release notes](https://github.com/substack/minimist/releases)
- [Commits](https://github.com/substack/minimist/compare/1.2.5...1.2.6)

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

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

Author: dependabot[bot]

backend/package-lock.json

@@ -27,7 +27,7 @@
     "firebase-admin": "^8.10.0",
     "firebase-functions": "^3.6.1",
     "jsonwebtoken": "^8.5.1",
-    "minimist": ">=1.2.3",
+    "minimist": ">=1.2.6",
     "mongoose": "^5.9.27",
     "validator": "^12.2.0"
   },