Bump ajv from 6.8.1 to 6.12.3 in /client

Bumps [ajv](https://github.com/ajv-validator/ajv) from 6.8.1 to 6.12.3.
- [Release notes](https://github.com/ajv-validator/ajv/releases)
- [Commits](ajv-validator/ajv@v6.8.1...v6.12.3)

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

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

Author: dependabot[bot]

client/package-lock.json

@@ -12,7 +12,7 @@
     "@mui/icons-material": "^5.2.5",
     "@mui/material": "^5.2.8",
     "@mui/styles": "^5.3.0",
-    "ajv": "6.8.1",
+    "ajv": "6.12.3",
     "axios": "^0.21.4",
     "eslint": "^8.11.0",
     "eslint-plugin-react": "7.28.0",