Release v6.7.0

[rashidakanchwala]

Description

This is minor release with big backend refactoring work and some bug fixes.

Bug fixes and other changes

• Refactor flowchart dataclasses to pydantic base models. (Refactor Flowchart models from dataclass to pydantic base models #1565)
• Fix dataset factory patterns in Experiment Tracking. (Fix dataset factory patterns in Experiment Tracking #1588)
• Update demo-project to use OmegaConfigLoader. (Update demo project to use OmegaConfigLoader #1590)
• Improve feedback for copy to clipboard feature. (Add tooltip to shareable urls copy button #1614)
• Ensure Kedro-Viz works when hosted on a URL subpath. (Fix: Kedro-Viz doesn't work when hosted via a URL subpath #1621)
• Bump fastapi upper bounds. (Bump FAST API upper bounds #1634)
• Fix shareable URL modal to appear across the app. (Make shareable URL modal open globally across the app.  #1639)
• Add Kedro-Viz CLI command deprecation warning. (Add kedro viz deprecation warning for CLI #1641)

Development notes

QA notes

Checklist

• Read the contributing guidelines
• Opened this PR as a 'Draft Pull Request' if it is work-in-progress
• Updated the documentation to reflect the code changes
• Added new entries to the RELEASE.md file
• Added tests to cover my changes

[NeroOkwa]

LGTM!

[jitu5]

LGTM!