Svelte: Remove babel/core peer dep

[IanVS]

Issue: N/A

https://discord.com/channels/486522875931656193/495147526278610945/1064676166092476566

What I did

I have removed babel/core from peerDependencies, as it is no longer used at all in this package.

How to test

CI should be sufficient. After the release, we can install storybook in a svelte project with pnpm and verify no dep warnings.

Checklist

• Make sure your changes are tested (stories and/or unit, integration, or end-to-end tests)
• Make sure to add/update documentation regarding your changes
• If you are deprecating/removing a feature, make sure to update
  MIGRATION.MD

Maintainers

• If this PR should be tested against many or all sandboxes,
  make sure to add the ci:merged or ci:daily GH label to it.
• Make sure this PR contains one of the labels below.

["cleanup", "BREAKING CHANGE", "feature request", "bug", "documentation", "maintenance", "dependencies", "other"]

[benmccann]

Thanks!