Disable the "Directory already exists" warning in Windows installer

Because of course the directory exists, it's a plugin.

cmake/bundle/windows/installer-Windows.iss.in

@@ -19,6 +19,7 @@ DefaultGroupName={#MyAppName}
 OutputBaseFilename={#MyAppName}-{#MyAppVersion}-Windows-Installer
 Compression=lzma
 SolidCompression=yes
+DirExistsWarning=no
 
 [Languages]
 Name: "english"; MessagesFile: "compiler:Default.isl"