Unable to upgrade to 1.4.1 on Squeeze (Debian 6)

I'm trying to upgrade MaxScale from 1.3.0 to 1.4.1 using apt:

# wget https://downloads.mariadb.com/enterprise/4d7m-n51s/generate/10.1/mariadb-enterprise-repository.deb
# dpkg -i mariadb-enterprise-repository.deb
# apt-get update
.......................

Err http://downloads.mariadb.com squeeze/main amd64 Packages
404 NOT FOUND
Ign http://downloads.mariadb.com squeeze/main amd64 Packages
Hit http://downloads.mariadb.com squeeze/main amd64 Packages
Get:3 http://downloads.mariadb.com squeeze/main amd64 Packages [20 B]
Err http://downloads.mariadb.com squeeze/main amd64 Packages
404 NOT FOUND
Fetched 2,092 B in 10s (202 B/s)
W: Failed to fetch http://downloads.mariadb.com/enterprise/4d7m-n51s/mariadb-enterprise/10.0/repo/debian/dists/squeeze/main/binary-amd64/Packages.gz 404 NOT FOUND

W: Failed to fetch http://downloads.mariadb.com/enterprise/4d7m-n51s/mariadb-maxscale/latest/debian/dists/squeeze/main/binary-amd64/Packages.gz 404 NOT FOUND

E: Some index files failed to download, they have been ignored, or old ones used instead.

It looks like squeeze packages are no longer provided by MariaDB, although the mariadb-enterprise-repository.deb tool still creates them:

cat /etc/apt/sources.list.d/mariadb-enterprise.list
# MariaDB Enterprise
deb http://downloads.mariadb.com/enterprise/4d7m-n51s/mariadb-enterprise/10.1/repo/debian squeeze main

# MariaDB MaxScale
deb http://downloads.mariadb.com/enterprise/4d7m-n51s/mariadb-maxscale/latest/debian squeeze main

# MariaDB Enterprise Tools
deb http://downloads.mariadb.com/enterprise/4d7m-n51s/mariadb-enterprise-tools/debian squeeze main

# MariaDB Enterprise Pilot
# These packages should be evaluated in a non-production environment. Please share your experiences with us
# and let us know if you find problems or have suggestions about how to improve these packages.
deb http://downloads.mariadb.com/enterprise/4d7m-n51s/mariadb-enterprise-pilot/10.1/debian squeeze main