d/chagenlog: target version is now 3.0.26+dfsg0-1

We were originally packaging 3.0.26+dfsg0, but upstream didn't show
that in the tarball name.

Upstream is now git-tagging releases, thus we are using 3.0.26+dfsg0.

Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>