Bump the octool timestamp.

The problem is the link-grammar-5.12.5 build breaks after the
recent changes to the atompsace header files. So those are fixed
in link-grammar 5.12.6 and we need to force those to be picked up.

Author: linas

opencog/base/Dockerfile

@@ -28,7 +28,8 @@ RUN apt-get -y install openssh-client
 
 # Install ocpkg. Bump the date to get the latest ocpkg installed;
 # Otherwise, this docker build will be cached with an old octool.
-ENV LAST_OCPKG_UPDATE 2025-06-12
+# And with old versions of those packages that octool installs.
+ENV LAST_OCPKG_UPDATE 2025-07-29
 
 # The OCPKG_URL can be overridden by specifying
 # docker build --build-arg OCPKG_URL=https://some.where.else.com/ockpg