Install latest GNU Octave

GNU Octave offers the syntax of Matlab in an open-source software suite. Octave binaries are readily installed:

• macOS: brew install octave
• Windows: winget install GNU.Octave
• Linux: Flatpak

For Linux, Flatpak may already be installed by the Linux distro. The flathub repo is added by:

flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo