Bump WP tested-up-to version and stable tag

[s3rgiosan]

Description of the Change

Testing has been done on WP 6.7 and all functionality appears to work as expected. This PR bumps the tested up to version to 6.7 and the stable tag to 1.6.0
Closes #49
Also closes #84

How to test the Change

Changelog Entry

Changed - Bump WordPress "tested up to" version to 6.7
Changed - Bump plugin version

Credits

Props @s3rgiosan

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added Critical Flows, Test Cases, and/or End-to-End Tests to cover my change.
• All new and existing tests pass.

[jeffpaul]

@s3rgiosan ahead of approving/merging this in a couple questions...

1. Are you able to help review/test/merge in any Dependabot bump PRs?
2. Are you ok if we add develop branch to set as the default branch and work on a more standard git branch and release flow like our other OSS projects?
3. Is there anything else you have targeted for a 1.6.0 release (open issues to consider, non-Dependabot PRs)?

[s3rgiosan]

@jeffpaul

Are you able to help review/test/merge in any Dependabot bump PRs?

Will do.

Are you ok if we add develop branch to set as the default branch and work on a more standard git branch and release flow like our other OSS projects?

Totally agree.

Is there anything else you have targeted for a 1.6.0 release (open issues to consider, non-Dependabot PRs)?

I can test this pull request: #70 to check for any deprecations. If everything looks good, I’d suggest including it in the 1.6.0 release.

I've also started working on this issue: #78, which focuses on exposing relationships in a REST endpoint and refactoring the UI to align with the block editor’s design. Since the UI will be transitioned from Vue to React, I’d recommend pausing or marking other UI-related issues as "won't fix" to avoid redundant work.