Project: add compat for Statistics

[benlorenz]

Statistics is now an upgradeable stdlib on nightly, see JuliaLang/julia#46501.

This is causing the Aqua test to fail in PkgEval: https://s3.amazonaws.com/julialang-reports/nanosoldier/pkgeval/by_date/2023-10/01/Singular.primary.log

     Testing Running tests...
Singular [bcd08a7b-43d2-5ff7-b6d4-c458787f915c] does not declare a compat entry for the following deps:
1-element Vector{Base.PkgId}:
 Statistics [10745b16-79ce-11e8-11f9-7d13ad32a3b2]
Compat bounds: Test Failed at /home/pkgeval/.julia/packages/Aqua/dInrs/src/deps_compat.jl:21
  Expression: isempty(result)
   Evaluated: isempty(Base.PkgId[Statistics [10745b16-79ce-11e8-11f9-7d13ad32a3b2]])

Lets see if this works in the CI here.

The same compat was already added to the registry: https://github.com/JuliaRegistries/General/blob/master/S/Singular/Compat.toml#L268