Dear Tiago,
the installation wiki [1] lists impish as a supported distro but the
corresponding apt folder on the server [2] is empty.
Is it indeed supposed to contain a deb or is it an issue with the
documentation?
[1]:
https://git.skewed.de/count0/graph-tool/-/wikis/installation-instructions#debian-ubuntu
[2]: https://downloads.skewed.de/apt/dists/impish/
Thanks in advance