Esmvaltool: setup.jl fails due to YAML (in)compatibility with Compat 3.5

[jhardenberg]

While running julia setup.jl installation of packages fails for YAML, due to the fact that YAML is restricted to Compat versions up to 2.*, but Compat 3.5 has been installed just before.

┌ Info: Installing
└   pkgName = "YAML"
 Resolving package versions...
ERROR: LoadError: Unsatisfiable requirements detected for package YAML [ddb6d928]:
 YAML [ddb6d928] log:
 ├─possible versions are: 0.3.0-0.3.2 or uninstalled
 ├─restricted to versions * by an explicit requirement, leaving only versions 0.3.0-0.3.2
 └─restricted by compatibility requirements with Compat [34da2185] to versions: uninstalled — no versions left
   └─Compat [34da2185] log:
     ├─possible versions are: [1.0.0-1.0.1, 1.1.0, 1.2.0, 1.3.0, 1.4.0, 1.5.0-1.5.1, 2.0.0, 2.1.0, 2.2.0, 3.0.0, 3.1.0, 3.2.0, 3.3.0-3.3.1, 3.4.0, 3.5.0] or uninstalled
     └─restricted to versions 3.5.0 by an explicit requirement, leaving only versions 3.5.0

[jhardenberg]

Explanation:
The problem was previously masked by the fact that RainFARM.jl was installing Compat <= 2.* , (see #1530 ), but now this requirement has been dropped in the new version RainFARM v1.1.0 .
Due to this setup.jl installs first Compat.jl v3.5, but then when it attempts to install YAML.jl (which is obviously badly configured) it fails since YAML.jl requires Compat <= 2.* .

Solution:
just moving the YAML package up in julia_requirements.txt before installing Compat solves the problem because YAML restricts Compat to v2.2. I did so in this branch and it works: https://github.com/ESMValGroup/ESMValTool/commit/542c234f2523c376c90f765351046d4eef874027
I could proceed with a PR from here.

[valeriupredoi]

so like this:

YAML
Compat
DataFrames
RainFARM
JSON
PyCall
PyPlot
NetCDF
Statistics

?
:beer:

[jhardenberg]

I tested the order in
https://github.com/ESMValGroup/ESMValTool/commit/542c234f2523c376c90f765351046d4eef874027
(actually switching YAML and Compat) and that one works

[jhardenberg]

@valeriupredoi I tested it and your version works too

[valeriupredoi]

Cool-mule, you wanna open a PR? I'll approve it first thing in the morrow and we good to go :beer: