Bump @mui/icons-material from 5.14.13 to 5.15.4

Bumps [@mui/icons-material](https://github.com/mui/material-ui/tree/HEAD/packages/mui-icons-material) from 5.14.13 to 5.15.4.
- [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/v5.15.4/packages/mui-icons-material)

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

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

package.json

@@ -29,7 +29,7 @@
   "devDependencies": {
     "@emotion/react": "^11.11.1",
     "@emotion/styled": "^11.11.0",
-    "@mui/icons-material": "^5.14.13",
+    "@mui/icons-material": "^5.15.4",
     "@mui/material": "^5.14.13",
     "@primer/octicons-react": "^19.8.0",
     "@twemoji/api": "^14.1.2",