I have often observed this: A release of a package has long been made on Github, but if I upgrade it with apt, it is not found. Example:
https://github.com/libgeos/geos : They show that 3.9 has already been released for Ubuntu.
sudo apt-get install --upgrade libgeos-dev, however, gives me 3.8.0-1build1.
Is there a special cause for this? Why do not people upload their code so that it can get installed by apt?
Thanks.