client-npm: bump @mui/material from 5.14.18 to 5.15.19 in /client

Bumps [@mui/material](https://github.com/mui/material-ui/tree/HEAD/packages/mui-material) from 5.14.18 to 5.15.19.
- [Release notes](https://github.com/mui/material-ui/releases)
- [Changelog](https://github.com/mui/material-ui/blob/v5.15.19/CHANGELOG.md)
- [Commits](https://github.com/mui/material-ui/commits/v5.15.19/packages/mui-material)

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

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

client/package.json

@@ -44,7 +44,7 @@
     "@emotion/styled": "^11.11.0",
     "@fontsource/roboto": "^5.0.8",
     "@mui/icons-material": "^5.14.8",
-    "@mui/material": "^5.14.8",
+    "@mui/material": "^5.15.19",
     "@reduxjs/toolkit": "^1.9.7",
     "@types/styled-components": "^5.1.32",
     "@typescript-eslint/eslint-plugin": "^6.12.0",