Release v1.4.0-beta

[danielmorell]

Description of the change

This is a releaase PR for v1.4.0-beta. It includes the following changes...

• Added support for Python 3.14 in #484
• Added support for error correlation headers in #491

Type of change

• New release

Related issues

None

Checklists

Development

• Lint rules pass locally
• The code changed/added as part of this pull request has been covered with tests
• All tests related to the changed code pass in development

Code review

• This pull request has a descriptive title and information useful to a reviewer. There may be a screenshot or screencast attached
• "Ready for review" label attached to the PR and reviewers assigned
• Issue from task tracker has a link to this pull request
• Changes have been reviewed by at least one other engineer