Why is Synaptic version of Subversion not upgradeable?

[bill walton]

Greetings!

I'm running 8.04 LTS (64-bit) and installed Subversion 1.4.6 via the
Synaptic Package Manager.  I now need to upgrade to SVN version 1.5.
The package manager doesn't show SVN as upgradeable.  Has support for
SVN been discontinued?  What do I need to do to upgrade?

TIA,
Bill