Add lemon package to build dependencies

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. This tool is available for Homebrew (https://formulae.brew.sh/formula/lemon#default), so please add it to the build dependencies of the master branch build scripts.