Add lemon and gtk3 as build dependencies

Please add both lemon and the development files for gtk3 as build dependencies for the master nightly build (these are not needed for 5.1), and GTK3 as a runtime dependency.

• lemon is needed as one possible way to fix kicad/code/kicad#5013 (closed) is to move the generated grammar files out of our source tree and into the build directory. To do this, every build will require the lemon tool now.
• gtk3 as a runtime dependency and the gtk3 development files will be needed to implement the move to trash feature currently in development.