Mpv/client.h: No such file or directory

Hello ones,
trying to compile minitube as far as it is outdated and do not working from the Flatpak. But the instructions on how to build deal with Debian based distro…

You need Qt >= 5.12 and MPV >= 0.29.0. The following Qt modules are needed: core, gui, widgets, network, sql (using the Sqlite plugin), declarative, dbus, x11extras.

I decided to go step-by-step, issued sudo swupd bundle-add devpkg-qtbase
and started qmake. Thus the compiler argued each time some package was missing, I searched for it via sudo swupd bundle-list or sudo swupd search and installed.

But where is mpv/client.h I do not found. Internet search gives the following package names for that header mpv-dev or libmpv-dev neither of which appears after search command.