Removing old version (#6420)

## What are you changing in this pull request and why?
 V1.6 was removed

## Checklist
- [ ] I have reviewed the [Content style
guide](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/content-style-guide.md)
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](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#adding-a-new-version)
and/or [version a block of
content](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#versioning-blocks-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](https://docs.getdbt.com/docs/dbt-versions/dbt-cloud-release-notes).
<!--
PRE-RELEASE VERSION OF dbt (if so, uncomment):
- [ ] Add a note to the prerelease version [Migration
Guide](https://github.com/dbt-labs/docs.getdbt.com/tree/current/website/docs/docs/dbt-versions/core-upgrade)
-->
<!-- 
ADDING OR REMOVING PAGES (if so, uncomment):
- [ ] Add/remove page in `website/sidebars.js`
- [ ] Provide a unique filename for new pages
- [ ] Add an entry for deleted pages in `website/vercel.json`
- [ ] Run link testing locally with `npm run build` to update the links
that point to deleted pages
-->

---------

Co-authored-by: Mirna Wong <89008547+mirnawong1@users.noreply.github.com>

website/dbt-versions.js

@@ -74,12 +74,5 @@ exports.versionedPages = [
  * @property {string} firstVersion The first version the category is visible in the sidebar
  */
 exports.versionedCategories = [
-  {
-    category: "Model governance",
-    firstVersion: "1.5",
-  },
-  {
-    category: "Build your metrics",
-    firstVersion: "1.6",
-  },
+
 ];