Describe the bug

When running lighteval tasks inspect "lighteval|gsm8k|0", an error is encountered: 'str' object has no attribute 'category'. This is because the tinyBenchmark tasks metrics have not been updated to be Metric classes (https://github.com/huggingface/lighteval/blob/main/src/lighteval/tasks/extended/tiny_benchmarks/main.py#L259)

To Reproduce

Run lighteval tasks inspect "lighteval|gsm8k|0" in the command line.

Expected behavior

Command successfully executes and task information for gsm8k is displayed to the user.

Version info

Commit 5137e03 on main