Increment version after release

[azure-sdk]

Increment package version after release

[Copilot]

Pull Request Overview

This PR increments the package version from 0.5.8 to 0.5.9 as part of the post-release process. It prepares the codebase for the next development cycle.

• Updates the version number in Directory.Build.props from 0.5.8 to 0.5.9
• Adds a new unreleased section in CHANGELOG.md for version 0.5.9
• Updates the CHANGELOG.md header from "CHANGELOG 📝" to "Release History"

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
Directory.Build.props	Increments version number from 0.5.8 to 0.5.9
CHANGELOG.md	Adds unreleased section for 0.5.9 and updates header formatting

[Copilot]

The changelog header has been changed from 'CHANGELOG 📝' to 'Release History', but this formatting change is not documented in the changelog entry. Consider adding this header change to the 'Other Changes' section.

[joshfree]

@weshaggard it would be nice if this auto-pr preserved the existing header

[weshaggard]

The header is backed into the existing changelog parser we use which is why it keeps resetting.

I'm guessing this will not be an issue after we change how we create the log

[weshaggard]

Fixed in microsoft/mcp#33

[weshaggard]

@hallipr this is another area that will need updating with the repo move as we need to update the correct server.