[dnm] try adding a workflow specific to ubuntu 20.04

Author: glessard

.github/workflows/pull_request.yml

@@ -6,49 +6,10 @@ on:
 
 jobs:
   tests:
-    name: Test
+    name: Test Supported Configurations Ubuntu 20.04
     uses: swiftlang/github-workflows/.github/workflows/swift_package_test.yml@main
     with:
-      linux_os_versions: '["noble", "jammy"]'
-      enable_macos_checks: true
-      # FIXME: https://github.com/swiftlang/github-workflows/pull/140
-      # Xcode 16.0 and 16.1 are not actually available
-      macos_exclude_xcode_versions: |
-        [
-          {"xcode_version": "16.0"},
-          {"xcode_version": "16.1"},
-        ]
-      swift_flags: "-Xbuild-tools-swiftc -DSYSTEM_CI"
-      enable_linux_static_sdk_build: true
-      enable_wasm_sdk_build: true
-
-  build-abi-stable:
-    name: Build ABI Stable
-    uses: swiftlang/github-workflows/.github/workflows/swift_package_test.yml@main
-    with:
-      enable_linux_checks: false
-      enable_macos_checks: true
+      linux_os_versions: '["jammy"]'
+      linux_exclude_swift_versions: '"[\"nightly-main\", \"nightly-6.2\"]"'
       enable_windows_checks: false
-      # Only build
-      macos_build_command: "xcrun swift build --build-tests"
-      # FIXME: https://github.com/swiftlang/github-workflows/pull/140
-      # Xcode 16.0 and 16.1 are not actually available
-      macos_exclude_xcode_versions: |
-        [
-          {"xcode_version": "16.0"},
-          {"xcode_version": "16.1"},
-        ]
-      # Enable availability to match ABI stable verion of system.
-      swift_flags: "-Xbuild-tools-swiftc -DSYSTEM_CI -Xbuild-tools-swiftc -DSYSTEM_ABI_STABLE"
-
-  soundness:
-    name: Soundness
-    uses: swiftlang/github-workflows/.github/workflows/soundness.yml@main
-    with:
-      license_header_check_project_name: "Swift.org"
-      # https://github.com/apple/swift-system/issues/224
-      docs_check_enabled: false
-      unacceptable_language_check_enabled: false
-      license_header_check_enabled: false
-      format_check_enabled: false
-      python_lint_check_enabled: false
+      enable_macos_checks: false