ci: add step to release script that updates the latest tag

[dominikg]

see #686

What this step does.

• put publishedPackages into an env var
• echo and pipe that into jq that maps it into package@version strings
• loop over these and call echo npm dist-tag add package@version latest for each published package

The called command is echoed for now to make sure it is correct.

After we verified it works we can remove the echo.

Please don't delete this checklist! Before submitting the PR, please make sure you do the following:

• It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https:/sveltejs/rfcs
• This message body should clearly illustrate what problems it solves.
• Ideally, include a test that fails without this PR but passes with it.

Tests

• Run the tests with pnpm test and lint the project with pnpm lint and pnpm check

Changesets

• If your PR makes a change that should be noted in one or more packages' changelogs, generate a changeset by running pnpx changeset and following the prompts. All changesets should be patch until SvelteKit 1.0

[changeset-bot]

⚠️ No Changeset found

Latest commit: 5b47430

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[dominikg]

this step would essentially turn into a noop (set latest to same version it was set to by the publish step before) once we exit pre-release mode but it should be removed then.

[dominikg]

jq is included in the ubuntu environment https:/actions/virtual-environments/blob/main/images/linux/Ubuntu2004-Readme.md

[Rich-Harris]

nice! excited to see if this works