git: openjdk/jdk21u: master: 8315863: [GHA] Update checkout action to use v4

[Aleksey Shipilev]

Changeset: 8565c710
Author:    Christian Stein <cstein at openjdk.org>
Committer: Aleksey Shipilev <shade at openjdk.org>
Date:      2023-09-11 10:17:34 +0000
URL:       https://git.openjdk.org/jdk21u/commit/8565c71036b68aa1d41590420da444afc6aebdcc

8315863: [GHA] Update checkout action to use v4

Backport-of: b74805d38395ca8be9308d882bf6b84e93714849

! .github/actions/get-gtest/action.yml
! .github/actions/get-jtreg/action.yml
! .github/workflows/build-cross-compile.yml
! .github/workflows/build-linux.yml
! .github/workflows/build-macos.yml
! .github/workflows/build-windows.yml
! .github/workflows/test.yml