Release V1.20.0

[YunchuWang]

Summary

What changed?

Why is this change needed?

Issues / work items

• Resolves #
• Related #

---

Project checklist

• Release notes are not required for the next release
  • Otherwise: Notes added to release_notes.md
• Backport is not required
  • Otherwise: Backport tracked by issue/PR #issue_or_pr
• All required tests have been added/updated (unit tests, E2E tests)
• Breaking change?
  • If yes:
    • Impact:
    • Migration guidance:

---

AI-assisted code disclosure (required)

Was an AI tool used? (select one)

• No
• Yes, AI helped write parts of this PR (e.g., GitHub Copilot)
• Yes, an AI agent generated most of this PR

If AI was used:

• Tool(s):
• AI-assisted areas/files:
• What you changed after AI output:

AI verification (required if AI was used):

• I understand the code and can explain it
• I verified referenced APIs/types exist and are correct
• I reviewed edge cases/failure paths (timeouts, retries, cancellation, exceptions)
• I reviewed concurrency/async behavior
• I checked for unintended breaking or behavior changes

---

Testing

Automated tests

• Result: Passed / Failed (link logs if failed)

Manual validation (only if runtime/behavior changed)

• Environment (OS, .NET version, components):
• Steps + observed results:
  1.
  2.
  3.
• Evidence (optional):

---

Notes for reviewers

• N/A

[Copilot]

Pull request overview

This PR prepares version 1.20.0 for release by updating the version number and documenting the changes in the CHANGELOG.

Changes:

• Version bumped from 1.19.1 to 1.20.0 in Release.props
• CHANGELOG.md updated with three new features for the 1.20.0 release: partial orchestration work item completion support, export history job functionality, and dependency injection support for DurableTaskTestHost

Reviewed changes

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

File	Description
eng/targets/Release.props	Updates VersionPrefix from 1.19.1 to 1.20.0
CHANGELOG.md	Adds 1.20.0 section documenting three new features included in this release

[Copilot]

The version header format is inconsistent with the rest of the CHANGELOG. All other version entries use the "v" prefix (e.g., "## v1.19.1", "## v1.19.0", etc.), but this entry uses "## 1.20.0" without the prefix. This should be changed to "## v1.20.0" to maintain consistency with the established convention in this file.

[Copilot]

Spelling error: "workitem" should be two words: "work item".

Suggested change

	- Partial orchestration workitem completion support (merge after next dts dp release) by wangbill ([#514](https://github.com/microsoft/durabletask-dotnet/pull/514))
	- Partial orchestration work item completion support (merge after next dts dp release) by wangbill ([#514](https://github.com/microsoft/durabletask-dotnet/pull/514))