[Bug] Update PyPI to point at the `stable` branch for the changelog and not at `main`

[dbeatty10]

It's really hard to find the "real" changelogs right now. We need to make it easy.

Two things:

1. Update links in PyPI
2. Update/add links in the main branch to point people towards the stable branch

Originally posted by @emmyoop in #1734:

Changelogs for the adapters live on the stable branch as that is the branch we release the minor patches from. They do not live on main. See dbt-snowflake changelog here.

I would suggest we update PyPI to point at this branch for the changelog and not at main.

Also, delete the content of files like this, and include a link to the changelog on the stable branch instead.