Update actions/cache action to v6

[Nice3point]

This PR contains the following updates:

Package	Type	Update	Change
actions/cache	action	major	v5 → v6

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Release Notes

actions/cache (actions/cache)

v6

Compare Source

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[Copilot]

Pull request overview

This PR updates the GitHub Actions dependency actions/cache from v5 to v6 across the repository’s compile and release-publish workflows (root workflows, template solution workflows, and the matching sample workflows), keeping CI behavior consistent while moving to the latest major of the cache action.

Changes:

• Bumped actions/cache usage from @v5 to @v6 in all affected workflows.
• Kept cache configuration (NuGet path, key, restore-keys) unchanged to preserve existing caching behavior.
• Updated both template-contained workflows and sample workflows to remain in sync with the root workflows.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
source/Nice3point.Revit.Templates/Nice3point.Revit.AddIn.Solution/.github/workflows/PublishRelease.yml	Updates NuGet package caching step to use actions/cache@v6 in the template solution release workflow.
source/Nice3point.Revit.Templates/Nice3point.Revit.AddIn.Solution/.github/workflows/Compile.yml	Updates NuGet package caching step to use actions/cache@v6 in the template solution compile workflow.
samples/MultiProjectSolution/.github/workflows/PublishRelease.yml	Updates NuGet package caching step to use actions/cache@v6 in the sample release workflow.
samples/MultiProjectSolution/.github/workflows/Compile.yml	Updates NuGet package caching step to use actions/cache@v6 in the sample compile workflow.
.github/workflows/PublishRelease.yml	Updates NuGet package caching step to use actions/cache@v6 in the repo release workflow.
.github/workflows/Compile.yml	Updates NuGet package caching step to use actions/cache@v6 in the repo compile workflow.

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