Building the project takes very long: too many dependencies

[luisaforozco]

I noticed when building the project from scratch that it takes very long to download and compile all dependencies.

We should check which dependencies are we indeed using and remove everything unused to speed up the project build.

[v1kko]

Best practices for optional dependencies: https://pkgdocs.julialang.org/v1/creating-packages/#Weak-dependencies