Allow multiple values in the `default` attribute in the profile yaml file

[xmnlab]

Currently, the default attribute accept just string

[YurelyCamacho]

@xmnlab Could you give me more information about this issue and if you can add the size label, please.

[xmnlab]

currently in a profile file, we can just have 1 string as default, it would be nice to allow a list of strings

refs:

• https://github.com/osl-incubator/scicookie/blob/main/src/scicookie/cli.py#L80
• https://github.com/osl-incubator/scicookie/blob/main/src/scicookie/profiles/osl.yaml#L95