Fix path separator in nuget push

build.js

@@ -26,6 +26,6 @@ if (bt.options.official)
 
     // Push nuget package
     bt.run(`dotnet nuget push`,
-           `./Build/Release/*.${bt.options.version.build}.nupkg`,
+           `.\\Build\\Release\\*.${bt.options.version.build}.nupkg`,
            `--source nuget.org`);
 }