Consider removing dependency on Pkg

[sumiya11]

On Julia 1.11+, loading Pkg might not be free anymore :

julia> @time_imports using Nemo
    ...
    586.6 ms  Pkg
    ...

Welcome to Nemo version 0.45.7

Nemo comes with absolutely no warranty whatsoever
               ┌ 487.9 ms Nemo.__init__() 9.25% compilation time
    749.8 ms  Nemo 6.02% compilation time

It seems that Pkg is used for determining the version of Nemo :

Nemo.jl/src/Nemo.jl

Line 386 in 8fac1af

const deps = Pkg.dependencies()

Maybe Base.get_pkgversion_from_path or similar can be used as a cheaper replacement :

julia> Base.get_pkgversion_from_path("../Nemo.jl/")
v"0.38.2"