Add December 2025 release notes

[shazron]

Added release notes for December 2025, detailing updates and fixes for @adobe/aio-lib-ims-oauth.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[Copilot]

Pull request overview

This PR adds release notes for December 2025 to document the @adobe/aio-lib-ims-oauth 6.0.5 patch release, which addresses several aio login issues, particularly on Windows platforms.

Changes:

• Added a new December 2025 section to the release notes with details about @adobe/aio-lib-ims-oauth 6.0.5 bug fixes

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[shazron]

The lint failing check is unrelated to the PR content. Filed an issue: #462
Recommend overriding and merging regardless.