add libqt5svg5-dev package to BUILD.md

[ParsaNobahari]

getting a build Debian/Ubuntu-based distros requires libqt5svg5-dev which wasn't mentioned unless I've missed something. tested on Ubuntu 24.04 LTS

error without installing said package:

Project ERROR: Unknown module(s) in QT: svg
make: *** [Makefile:73: sub-src-make_first] Error 3