Update dependency next to ^15.5.8

Author: renovate[bot]

package.json

@@ -20,7 +20,7 @@
   "dependencies": {
     "graphql": "^16.10.0",
     "graphql-request": "^7.1.2",
-    "next": "^15.1.7",
+    "next": "^15.5.8",
     "ofetch": "^1.4.1",
     "react": "^19.2.1",
     "react-dom": "^19.2.1",