[Core] Update Azure Core to 1.57.0

[notyashhh]

Description

Mandatory Checklist

• Please choose the target release of Azure PowerShell. (⚠️Target release is a different concept from API readiness. Please click below links for details.)

  • General release
  • Public preview
  • Private preview
  • Engineering build
  • No need for a release

• Check this box to confirm: I have read the Submitting Changes section of CONTRIBUTING.md and reviewed the following information:

• SHOULD update ChangeLog.md file(s) appropriately
  • Update src/{{SERVICE}}/{{SERVICE}}/ChangeLog.md.
    • A snippet outlining the change(s) made in the PR should be written under the ## Upcoming Release header in the past tense.
  • Should not change ChangeLog.md if no new release is required, such as fixing test case only.
• SHOULD regenerate markdown help files if there is cmdlet API change. Instruction
• SHOULD have proper test coverage for changes in pull request.
• SHOULD NOT adjust version of module manually in pull request

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[Copilot]

Pull request overview

Updates centrally managed shared dependencies used across Azure PowerShell (primarily Az.Accounts and shared src/lib assemblies) to align with Azure SDK package revisions.

Changes:

• Bumped Azure.Core from 1.56.0 to 1.57.0 across compile-time references, shared assembly manifest, and assembly loading metadata.
• Bumped System.ClientModel from 1.12.0 to 1.13.0 in shared assembly manifest and metadata.
• Updated Az.Accounts changelog entry under Upcoming Release to reflect the dependency bumps.

Reviewed changes

Copilot reviewed 5 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tools/Common.Netcore.Dependencies.targets	Updates the compile-time PackageReference for Azure.Core to 1.57.0.
src/lib/manifest.json	Updates shared dependency source-of-truth versions for Azure.Core and System.ClientModel.
src/lib/cgmanifest.json	Updates component governance metadata versions for Azure.Core and System.ClientModel.
src/Accounts/AssemblyLoading/ConditionalAssemblyProvider.cs	Updates generated assembly list to load Azure.Core/System.ClientModel with the new assembly versions.
src/Accounts/Accounts/ChangeLog.md	Updates Upcoming Release notes for the dependency upgrades.