[ENH][FIX] Tracker Filter: Resolve Deprecated Warning by Refining JsonSerializable Implementation for Clearer Return Type

This pull request enhances the codebase by resolving a deprecated warning in the implementation of the jsonSerialize() method. Previously, the method had been adjusted with a return type of mixed, but the actual return value was an array. To align with best practices and provide clearer code documentation, this update replaces the return type with array, accurately reflecting the nature of the returned data. This refinement ensures compatibility with modern PHP versions and adheres to the requirements of the JsonSerializable interface. From: https://app.glitchtip.com/evoludata/issues/2420797 & https://app.glitchtip.com/evoludata/issues/2379676