Verify no netstandard2.0 build references in repository

[Copilot]

Summary

This PR addresses issue #1780 which requests that netstandard2.0 references be removed from the build configuration to prevent future build breaks.

Analysis

After a comprehensive search of the entire repository, I confirmed that no netstandard2.0 references exist in the codebase. The repository is already in the desired state.

Current Build Configuration

The PSResourceGet module currently:

• Targets only net472 in the main project file (src/code/Microsoft.PowerShell.PSResourceGet.csproj)
• All CI/CD pipelines exclusively build with -BuildFramework 'net472':
  • .ci/ci.yml
  • .ci/ci_auto.yml
  • .ci/ci_release.yml
  • .pipelines/PSResourceGet-Official.yml
• Build script (build.ps1) restricts the framework parameter via [ValidateSet("net472")]
• Documentation (README.md) only includes examples using net472

Conclusion

No changes were required. The repository already meets the requirement of having no netstandard2.0 build references, preventing the type of build issues mentioned in #1779. All build infrastructure is configured to use net472 exclusively.

Closes #1780

Original prompt

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This section details on the original issue you should resolve

<issue_title>Build for target netstandard2.0 too in CI/CD</issue_title>
<issue_description>### Summary of the new feature / enhancement

If netstandard2.0 is a wanted target framework for PSResourceGet there should be automated tests / builds against it so build does not break in the future:

• Target framework "netstandard2.0" does not build with error The name 'Registry' does not exist in the current context #1779

From what I can see it does not seem CI/CD build for netstandard2.0 currently:

• https://github.com/search?q=repo%3APowerShell%2FPSResourceGet+path%3A%2F%5E%28%5C.ci%5C%2F%7C%5C.github%5C%2F%29%2F++build.ps1&type=code

Proposed technical implementation details (optional)

No response</issue_description>

<agent_instructions>Remove any references to build using 'netstandard2.0'</agent_instructions>

Comments on the Issue (you are @copilot in this section)

Fixes #1781

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