ci: run GDK on older Windows environment

>
> The GDK version which is set up by build-scripts/setup-gdk-desktop.py does not support Visual Studio 2026

.github/workflows/create-test-plan.py

@@ -27,6 +27,7 @@ class MsvcArch(Enum):
 
 class JobOs(Enum):
     WindowsLatest = "windows-latest"
+    Windows2022 = "windows-2022"
     UbuntuLatest = "ubuntu-latest"
     MacosLatest = "macos-latest"
     Ubuntu22_04 = "ubuntu-22.04"
@@ -118,7 +119,7 @@ JOB_SPECS = {
     "msvc-clang-x64": JobSpec(name="Windows (MSVC, clang-cl x64)",          os=JobOs.WindowsLatest,     platform=SdlPlatform.Msvc,        artifact="SDL-clang-cl-x64",       msvc_arch=MsvcArch.X64,   clang_cl=True, ),
     "msvc-clang-x86": JobSpec(name="Windows (MSVC, clang-cl x86)",          os=JobOs.WindowsLatest,     platform=SdlPlatform.Msvc,        artifact="SDL-clang-cl-x86",       msvc_arch=MsvcArch.X86,   clang_cl=True, ),
     "msvc-arm64": JobSpec(name="Windows (MSVC, ARM64)",                     os=JobOs.WindowsLatest,     platform=SdlPlatform.Msvc,        artifact="SDL-VC-arm64",           msvc_arch=MsvcArch.Arm64, msvc_project="VisualC/SDL.sln", ),
-    "msvc-gdk-x64": JobSpec(name="GDK (MSVC, x64)",                         os=JobOs.WindowsLatest,     platform=SdlPlatform.Msvc,        artifact="SDL-VC-GDK",             msvc_arch=MsvcArch.X64,   msvc_project="VisualC-GDK/SDL.sln", gdk=True, no_cmake=True, ),
+    "msvc-gdk-x64": JobSpec(name="GDK (MSVC, x64)",                         os=JobOs.Windows2022,     platform=SdlPlatform.Msvc,        artifact="SDL-VC-GDK",             msvc_arch=MsvcArch.X64,   msvc_project="VisualC-GDK/SDL.sln", gdk=True, no_cmake=True, ),
     "ubuntu-22.04": JobSpec(name="Ubuntu 22.04",                            os=JobOs.Ubuntu22_04,       platform=SdlPlatform.Linux,       artifact="SDL-ubuntu22.04", ),
     "ubuntu-latest": JobSpec(name="Ubuntu (latest)",                        os=JobOs.UbuntuLatest,      platform=SdlPlatform.Linux,       artifact="SDL-ubuntu-latest", ),
     "ubuntu-24.04-arm64": JobSpec(name="Ubuntu 24.04 (ARM64)",              os=JobOs.Ubuntu24_04_arm,   platform=SdlPlatform.Linux,       artifact="SDL-ubuntu24.04-arm64", ),