Improve solution file detection in OpenCVSharp build process

Author: xavave

.github/workflows/build-win-arm64.yml

@@ -220,7 +220,17 @@ jobs:
             Write-Host "Fixed jpeg.lib path in main vcxproj"
           }
           
-          msbuild OpenCVSharpExtern.sln /t:build /p:Configuration=Release /p:Platform=ARM64 /m:2
+          # Find the actual solution file generated by CMake
+          Write-Host "Looking for solution file..."
+          $slnFile = Get-ChildItem -Filter "*.sln" | Select-Object -First 1
+          if ($slnFile) {
+            Write-Host "Found solution file: $($slnFile.Name)"
+            msbuild $slnFile.Name /t:build /p:Configuration=Release /p:Platform=ARM64 /m:2
+          } else {
+            Write-Error "No .sln file found in build directory"
+            Get-ChildItem
+            exit 1
+          }
 
           
       - name: Upload Native Artifacts