Returntype of. as_classification_dataset is "TaskAwareClassificationDataset"

**Description**
Under [avalanche/avalanche/benchmarks/utils.py](https://github.com/ContinualAI/avalanche/blob/625e46d9203878ed51457f6d7cd8d4e9fb05d093/avalanche/benchmarks/utils/utils.py#L202) des return type of `as_classification_dataset` is a "TaskAwareClassificationDataset" even if it returns a "ClassificationDataset" (See screenshot).

**Expected behavior**
Return a `ClassificationDataset`

**Screenshot**

Open avalanche/avalanche/benchmarks/utils.py at the linked as_classification_dataset definition and compare its declared return type with the object it returns. Update the mismatch so the declaration reflects the expected ClassificationDataset, then verify that the function's type information and runtime behavior agree.

Written by the indexing model from the issue text.