Revert "Fix version number inclusion in gnucash.desktop file"

This reverts commit 9d8def84f3.

Another oops. The version number in the desktop file is not the
gnucash version but the desktop file specification version.
There are more recent specification versions available, but
we should only bump it after having verified our desktop file
adheres to those higher versions. So revert for now.

gnucash/gnome/gnucash.desktop.in.in

@@ -1,7 +1,7 @@
 [Desktop Entry]
 Type=Application
 MimeType=application/x-gnucash;
-Version=@VERSION@
+Version=0.9.4
 _Name=GnuCash
 _GenericName=Finance Management
 _Comment=Manage your finances, accounts, and investments