.NET: Updating version for dotnet release 1.16.0

[SergeyMenshykh]

Motivation & Context

Version bump for the .NET 1.16.0 release.

Description & Review Guide

• What are the major changes? Updated VersionPrefix, DateSuffix, and GitTag in dotnet/nuget/nuget-package.props.
• What is the impact of these changes? All NuGet packages will use version 1.16.0.
• What do you want reviewers to focus on? N/A

Related Issue

N/A

Contribution Checklist

• The code builds clean without any errors or warnings
• All unit tests pass, and I have added new tests where possible
• The PR follows the Contribution Guidelines
• This PR is linked to an issue and there is no other open PR for this issue (see Related Issue above).
• This is not a breaking change. If it is a breaking change, add the breaking change label (or add "[BREAKING]" to the title prefix, before or after any language prefix) — a workflow keeps the label and title prefix in sync automatically.

[Copilot]

Pull request overview

Updates the centralized .NET NuGet package version metadata to prepare the repository for the 1.16.0 release, ensuring all packages produced from dotnet/ will carry the new release version identifiers.

Changes:

• Bumped the shared NuGet VersionPrefix from 1.15.0 to 1.16.0.
• Updated the preview/CI DateSuffix from 260722 to 260730.
• Updated the GitTag value from 1.15.0 to 1.16.0.

[github-actions]

Automated Code Review

Reviewers: 5 | Confidence: 92% | Result: All clear

Reviewed: Correctness, Security Reliability, Test Coverage, Failure Modes, Design Approach

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Automated review by SergeyMenshykh's agents

[github-actions]

Automated Code Review

Reviewers: 5 | Confidence: 93% | Result: All clear

Reviewed: Correctness, Security Reliability, Test Coverage, Failure Modes, Design Approach

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Automated review by SergeyMenshykh's agents