Bug#817138: education-main-server: please update links to Squid proxy
The Debian 'squid3' package has been renamed to 'squid' in
Testing/stretch. The 'squid3' package is now a transitional temporary
package that will be removed at some point.
Please update your package to "Recommends: squid".
If there are any other references to "squid3" in your package they will
also need to be updated. That includes file paths and documentation.