feat!(serve): pick an open port when 3000 is already taken

[pcattori]

Closes: #

• Docs
• Tests

Testing Strategy:

[changeset-bot]

🦋 Changeset detected

Latest commit: 1294bac

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 16 packages

Name	Type
@remix-run/serve	Major
@remix-run/dev	Major
create-remix	Major
remix	Major
@remix-run/architect	Major
@remix-run/cloudflare	Major
@remix-run/cloudflare-pages	Major
@remix-run/cloudflare-workers	Major
@remix-run/css-bundle	Major
@remix-run/deno	Major
@remix-run/eslint-config	Major
@remix-run/express	Major
@remix-run/node	Major
@remix-run/react	Major
@remix-run/server-runtime	Major
@remix-run/testing	Major

Not sure what this means? Click here to learn what changesets are.

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

[github-actions]

🤖 Hello there,

We just published version 2.0.0-pre.0 which includes this pull request. If you'd like to take it for a test run please try it out and let us know what you think!

Thanks!