Update dependency eslint-config-next to v15.5.12

Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

frontend/package.json

@@ -50,7 +50,7 @@
     "@typescript-eslint/parser": "6.21.0",
     "autoprefixer": "10.4.21",
     "eslint": "8.57.1",
-    "eslint-config-next": "15.3.5",
+    "eslint-config-next": "15.5.12",
     "eslint-config-prettier": "10.1.5",
     "postcss": "8.5.6",
     "prettier": "3.3.2",