Prepare core b5 release

[Hameedkunkanoor]

Description

This PR prepares a new prerelease for azure-ai-agentserver-core by:

• Bumping package version from 2.0.0b4 to 2.0.0b5.
• Adding a CHANGELOG entry for 2.0.0b5.
• Documenting the blueprint telemetry attribute key fix so the Python package release includes it.

Relevant changes:

• Python: Fix blueprint_id attribute key to microsoft.a365.agent.blueprint.id
  Fix blueprint_id attribute key to microsoft.a365.agent.blueprint.id #47094
• .NET (cross-SDK alignment reference): Fix blueprint_id attribute key to microsoft.a365.agent.blueprint.id
  Fix blueprint_id attribute key to microsoft.a365.agent.blueprint.id azure-sdk-for-net#59422

No API spec regeneration is included in this PR.

All SDK Contribution checklist:

• The pull request does not introduce breaking changes.
• CHANGELOG is updated for new features, bug fixes or other significant changes.
• I have read the contribution guidelines.

General Guidelines and Best Practices

• Title of the pull request is clear and informative.
• There are a small number of commits, each of which have an informative message.

Testing Guidelines

• Pull request includes test coverage for the included changes.

Testing note:

• This PR only updates versioning and changelog for release preparation.
• Functional validation is covered by the original feature/fix PR test runs (for example, Fix blueprint_id attribute key to microsoft.a365.agent.blueprint.id #47094).

[Copilot]

Pull request overview

Prepares the azure-ai-agentserver-core package for the 2.0.0b5 prerelease by bumping the package version and adding a corresponding release note entry.

Changes:

• Bumped package version from 2.0.0b4 to 2.0.0b5.
• Added a 2.0.0b5 CHANGELOG entry documenting the blueprint telemetry attribute key fix.

Reviewed changes

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

File	Description
sdk/agentserver/azure-ai-agentserver-core/CHANGELOG.md	Adds the 2.0.0b5 release notes entry (needs a small wording correction to reflect the actual attribute key rename).
sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/_version.py	Updates the package version constant to 2.0.0b5.