add libqt5svg5-dev package to BUILD.md

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
```