Bump @mui/material from 6.4.8 to 7.3.1 in /client

Bumps [@mui/material](https://github.com/mui/material-ui/tree/HEAD/packages/mui-material) from 6.4.8 to 7.3.1.
- [Release notes](https://github.com/mui/material-ui/releases)
- [Changelog](https://github.com/mui/material-ui/blob/master/CHANGELOG.md)
- [Commits](https://github.com/mui/material-ui/commits/v7.3.1/packages/mui-material)

---
updated-dependencies:
- dependency-name: "@mui/material"
  dependency-version: 7.3.1
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

client/package.json

@@ -28,7 +28,7 @@
   "dependencies": {
     "@emotion/react": "^11.14.0",
     "@emotion/styled": "^11.14.0",
-    "@mui/material": "^6.4.8",
+    "@mui/material": "^7.3.1",
     "axios": "^1.8.4",
     "react": "^19.1.0",
     "react-dom": "^19.1.0",