build(deps): bump @mui/material from 5.14.11 to 5.15.6 in /webgui-new

Bumps [@mui/material](https://github.com/mui/material-ui/tree/HEAD/packages/mui-material) from 5.14.11 to 5.15.6.
- [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/v5.15.6/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>

Author: dependabot[bot]

webgui-new/package-lock.json

@@ -34,7 +34,7 @@
     "@emotion/styled": "^11.10.5",
     "@mui/icons-material": "^5.11.0",
     "@mui/lab": "5.0.0-alpha.116",
-    "@mui/material": "^5.11.4",
+    "@mui/material": "^5.15.6",
     "@next/font": "~13.4.19",
     "@uiw/codemirror-theme-github": "^4.19.8",
     "@uiw/react-codemirror": "^4.19.6",