Update pull_request.yml drop debian12 for now

Author: shahmishal

.github/workflows/pull_request.yml

@@ -9,7 +9,7 @@ jobs:
     name: Test
     uses: swiftlang/github-workflows/.github/workflows/swift_package_test.yml@main
     with:
-      linux_os_versions: '["noble", "jammy", "focal", "rhel-ubi9", "debian12"]'
+      linux_os_versions: '["noble", "jammy", "focal", "rhel-ubi9"]'
       linux_swift_versions: '["6.1", "nightly-main"]'
       linux_build_command: 'swift build'
       windows_swift_versions: '["6.1", "nightly-main"]'