feat: use repo as source of truth

[sdn4z]

With this PR we start downloading the packages from our repo.

It contains some small refactoring in the TopXXReferences classes.

closes #313

BREAKING CHANGE

[scastlara]

Suggested change

	json_response = {"packages": packages, "date": datetime.datetime.now().isoformat}
	json_response = {"packages": packages, "date": datetime.datetime.now().isoformat()}

[scastlara]

We need to update the README, specifically this section where it says PyPI reference: https://github.com/elementsinteractive/twyn?tab=readme-ov-file#configuration-file

[scastlara]

And this is a breaking change, since we are changing the format input of one of the parameters of twyn.

[sdn4z]

And this is a breaking change, since we are changing the format input of one of the parameters of twyn.

I was still going through the PR, I didn't make it a draft because I thought I was going to finish before you'd jump into it (wrong assumption).

It is breaking indeed, I'll add it to the PR description.

All the changes related to the dependencies vendoring will be released on 4.0.0, so it was safe on that side, since it won't break any old implementations.