Cannot Install 2.5.5 on Windows 10 1511

I'm currently running SourceTree 2.4.7 on a system running Windows Pro 10 Version 1511.  As prompted by the notification icon on SourceTree, I tried to update to 2.5.5.  However, that version requires Windows .NET 4.7.1, which is not compatible with my version of Windows.

Now, the obvious answer for a private machine would be to update to a newer version of the OS.  However, this is machine is managed by our IT department (as would be the case with many of the users of SourceTree). Unless our IT department decides to push out an update, I'm stuck with that version.

Either a version that doesn't rely on the latest-and-greatest .NET would be useful, or at least a way to stop the automatic updates (as listed in issue SRCTREEWIN-2084).