[3.0] contrib: harfbuzz: update to 11.4.4 / gmp to 6.3.0
In the 3.4.0 update commit 6e3bfdbf, the 4.0 version was described as having massive API changes. However libass, our plugin and Qt all build fine with this version.
Debian trixie uses 10.2.0 1.
Update meson to 0.63 and require at least 0.60 so it can be built properly, while not switching to a 1.x version.
Switch to CMake to avoid upgrading meson which requires a newer version of Python than we have in the CI.
We don't need ragel as an external tool anymore. It's built within harfbuzz if it's not found on the system.
The Docker images include a newer version version of python necessary for the newer meson version.
Edited by Steve Lhomme