MAINT - Do not use `nodefaults` moving forward

[trallard]

Fixes https://github.com/conda-incubator/conda-store/issues/962

Description

• While reviewing another PR, I realised there are a lot of warnings regarding the use of nodefaults due to changes in conda and miniconda-setup related to removing the default population in channels. This PR makes the necessary updates to remove these warnings.
• Since I was touching workflows, I decided to add the attest-build-provenance-github configuration to our release action to also generate GH attestions

Pull request checklist

• [x] Did you test this change locally?
• [ ] Did you update the documentation (if required)?
• [ ] Did you add/update relevant tests for this change (if required)?

Additional information

How to test

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[trallard]

There is no harm in providing both, as they have slightly different schemas/metadata so let's just go with it.