fix(deps): update nextjs monorepo to v15.5.6 (#4314)

Co-authored-by: homarr-renovate[bot] <158783068+homarr-renovate[bot]@users.noreply.github.com>

packages/ui/package.json

@@ -35,7 +35,7 @@
     "@mantine/hooks": "^8.3.5",
     "@tabler/icons-react": "^3.35.0",
     "mantine-react-table": "2.0.0-beta.9",
-    "next": "15.5.5",
+    "next": "15.5.6",
     "react": "19.2.0",
     "react-dom": "19.2.0",
     "svgson": "^5.3.1"