build(deps): bump @mui/system from 5.15.15 to 5.15.20 (#1071)

Bumps [@mui/system](https://github.com/mui/material-ui/tree/HEAD/packages/mui-system) from 5.15.15 to 5.15.20.
- [Release notes](https://github.com/mui/material-ui/releases)
- [Changelog](https://github.com/mui/material-ui/blob/v5.15.20/CHANGELOG.md)
- [Commits](https://github.com/mui/material-ui/commits/v5.15.20/packages/mui-system)

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

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

package.json

@@ -14,7 +14,7 @@
     "@mui/icons-material": "^5.15.19",
     "@mui/lab": "=5.0.0-alpha.170",
     "@mui/material": "^5.15.19",
-    "@mui/system": "^5.15.13",
+    "@mui/system": "^5.15.20",
     "@stripe/stripe-js": "^2.4.0",
     "@types/node": "20.14.2",
     "@types/react": "18.3.3",