fix(deps): update mantine monorepo to v8

Author: renovate[bot]

frontend/package.json

@@ -18,10 +18,10 @@
     "@fullcalendar/daygrid": "^6.1.8",
     "@fullcalendar/interaction": "^6.1.5",
     "@fullcalendar/react": "^6.1.8",
-    "@mantine/core": "^6.0.13",
+    "@mantine/core": "^8.0.0",
     "@mantine/ds": "^6.0.13",
-    "@mantine/form": "^7.10.2",
-    "@mantine/hooks": "^6.0.13",
+    "@mantine/form": "^8.0.0",
+    "@mantine/hooks": "^8.0.0",
     "@mui/icons-material": "^5.11.16",
     "@mui/lab": "^5.0.0-alpha.124",
     "@mui/material": "^5.13.5",