office-addin-manifest validate doesn't recognize PowerPointApi 1.6

When using the PowerPointApi 1.6 req set in the manifest, the office-addin-manifest tool doesn't recognize it as valid. 1.5 and 1.7 req sets do work however.

• [x ] I am running the latest version of Node and the tools
• [x ] I checked the documentation and found no answer
• [x ] I checked to make sure that this issue has not already been filed

Expected behavior

The manifest should be valid.

Current behavior

Error #1:
No Supported Office Products: There are no platforms which fulfil the requirements specified in the manifest. The most common reasons for this failure are issues in the Requirements section. Please review the manifest and try again.

Error #2:
No Supported Products found for the package: undefined

The manifest is not valid.

Steps to Reproduce

1. Create a new PowerPoint project with yo office.
2. Add the following entry to the manifest.

<Requirements>
  <Sets DefaultMinVersion="1.1">
    <Set Name="PowerPointApi" MinVersion="1.6"/>
  </Sets>
</Requirements>

3. npm run validate

Context

Please provide any relevant information about your setup. This is important in case the issue is not reproducible except for under certain conditions.

• Operating System: Windows 11
• Node version: v22.14.0
• Office version: NA
• Tool version: office-addin-manifest 2.0.3

Failure Logs

none

Reproduce the failure with the PowerPointApi 1.6 manifest entry and npm run validate using office-addin-manifest 2.0.3. Trace the manifest requirement-set validation entry point and compare its handling of PowerPointApi 1.5, 1.6, and 1.7; done means the 1.6 manifest is accepted without either reported error.