add SLIM registry

[alisiahkoohi]

A fresh installation of InvertibleNetworks.jl according to README.md results in

(v1.6) pkg> dev https://github.com/slimgroup/InvertibleNetworks.jl
     Cloning git-repo `https://github.com/slimgroup/InvertibleNetworks.jl`
   Resolving package versions...
  Installing known registries into `~/.julia`
       Added registry `General` to `~/.julia/registries/General`
ERROR: Unsatisfiable requirements detected for package JOLI [bb331ad6]:
 JOLI [bb331ad6] log:
 ├─JOLI [bb331ad6] has no known versions!
 └─restricted to versions * by InvertibleNetworks [b7115f24] — no versions left
   └─InvertibleNetworks [b7115f24] log:
     ├─possible versions are: 2.0.0 or uninstalled
     └─InvertibleNetworks [b7115f24] is fixed to version 2.0.

I have included adding the SLIM registry in the installation process.

[codecov[bot]]

Codecov Report

Merging #29 (aadb536) into master (4e1eb09) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #29   +/-   ##
=======================================
  Coverage   84.16%   84.16%           
=======================================
  Files          31       31           
  Lines        2476     2476           
=======================================
  Hits         2084     2084           
  Misses        392      392           

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[mloubout]

Looks good, @philippwitte happy with it?

[alisiahkoohi]

@philippwitte Added the papers to this pull-request.