This updates pd-lua to the leatest version (0.10) for compatibility with Lua 5.4. Tested on Manjaro (Arch) with the lua54 package from the AUR.
While Lua 5.4 has been out for a little while now, it'll probably be some time until distributions ship it (even Arch is still on Lua 5.3 right now), because Lua has an extensive ecosystem of 3rd party libraries, and not all of these have been ported over to the new version yet.
Functionality-wise, there are hardly any user-visible changes in Lua 5.4, but there are some backward incompatibilities in the C API, one of which also broke pd-lua (upstream bug report by Claude Heiland-Allen). The present MR makes sure that we include the latest pd-lua version, to ease migration when distributions do start shipping Lua 5.4; just a recompile will then be enough to accommodate the new version.