fix: add compatibility layer to move to flask>=3

* flask-sqlalchemy moved pagination.

* this change has been added to have a smooth migration to flask>=3.0.0
  without creating a hard cut and major versions release.

invenio_banners/services/results.py

@@ -1,14 +1,22 @@
 # -*- coding: utf-8 -*-
 #
 # Copyright (C) 2022-2023 CERN.
+# Copyright (C) 2024 Graz University of Technology.
 #
 # Invenio-Banners is free software; you can redistribute it and/or modify it
 # under the terms of the MIT License; see LICENSE file for more details.
 
 """Service results."""
-from flask_sqlalchemy import Pagination
+
 from invenio_records_resources.services.records.results import RecordItem, RecordList
 
+try:
+    # flask_sqlalchemy<3.0.0
+    from flask_sqlalchemy import Pagination
+except ImportError:
+    # flask_sqlalchemy>=3.0.0
+    from flask_sqlalchemy.pagination import Pagination
+
 
 class BannerItem(RecordItem):
     """Single banner result."""