Bump System.Text.Json toolset version

[steveisok]

Resolves CG alert

[Copilot]

Copilot reviewed 1 out of 1 changed files in this pull request and generated no comments.

[steveisok]

/backport to release/9.0-staging

[github-actions]

Started backporting to release/9.0-staging: https://github.com/dotnet/runtime/actions/runs/13794006273

[carlossanlop]

I assume updating the toolset of S.T.J. does not have the same cascading effect on other repos as the regular S.T.J. package has, correct? cc @ericstj

[am11]

I assume updating the toolset of S.T.J. does not have the same cascading effect on other repos as the regular S.T.J. package has, correct? cc @ericstj

Isn't the opposite true based on the comment we added in 994e272 (i.e. this change needs to be coordinated with other repos + VS)?

[ViktorHofer]

No cascading effect as STJ with the toolset version doesn't get redistributed or promoted to a package dependency. It's a compile-only dependency. The only constraint is that the version used isn't newer than what ships inbox in VS (based on the VS images that we use in our CI).

[ericstj]

Also if we happen to ship any of the tasks built here, that the minimum version of VS required by the SDK also has the update.