Automatically install Python library dependencies

[mtfishman]

One thing we could try is moving the set of commands in the CI for installing AutoHOOT and cotengra into a file deps/build.jl, which Julia will run as a build step when the ITensorNetworkAD package gets installed. Similar to the discussions here:
https://discourse.julialang.org/t/pycall-pre-installing-a-python-package-required-by-a-julia-package/3316
https://gist.github.com/Luthaf/368a23981c8ec095c3eb

[mtfishman]

I guess we should actually add this as a build script in the AutoHOOT.jl package instead.