Core v1.9 RC updates

[matthewshaver]

What are you changing in this pull request and why?

Updates for Core v1.9 release candidate. Will add the date when it's available in a follow up for GA

Closes #6488

Checklist

• I have reviewed the Content style guide so my content adheres to these guidelines.
• The topic I'm writing about is for specific dbt version(s) and I have versioned it according to the version a whole page and/or version a block of content guidelines.
• I have added checklist item(s) to this list for anything anything that needs to happen before this PR is merged, such as "needs technical review" or "change base branch."
• The content in this PR requires a dbt release note, so I added one to the release notes page.

---

🚀 Deployment available! Here are the direct links to the updated files:

• https://docs-getdbt-com-git-one-nine-dbt-labs.vercel.app/docs/dbt-versions/core-upgrade/06-upgrading-to-v1.9

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Updated (UTC)
docs-getdbt-com	✅ Ready (Inspect)	Visit Preview	Nov 26, 2024 4:35am

[nataliefiann]

Hiya @matthewshaver

Thanks for creating this PR!
I've approved this for you.

Kind Regards
Natalie