test running CI on windows-2025 image

Author: baldurk

.github/workflows/ci.yml

@@ -104,25 +104,25 @@ jobs:
         name: [ VS2015 x86 Development, VS2015 x64 Development, VS2015 x64 Release, VS2019 x64 Development, VS2022 x64 Development ]
         include:
           - name: VS2015 x86 Development
-            os: windows-2019
+            os: windows-2025
             compiler: VS2015
             toolset: v140
             platform: x86
             configuration: Development
           - name: VS2015 x64 Development
-            os: windows-2019
+            os: windows-2025
             compiler: VS2015
             toolset: v140
             platform: x64
             configuration: Development
           - name: VS2015 x64 Release
-            os: windows-2019
+            os: windows-2025
             compiler: VS2015
             toolset: v140
             platform: x64
             configuration: Release
           - name: VS2019 x64 Development
-            os: windows-2019
+            os: windows-2025
             compiler: VS2019
             toolset: v142
             platform: x64