CI: fix GAMS by fixing TIMES_model path, NZ file structure

[olejandro]

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[olejandro]

@siddharth-krishna here is what this branch is about:

• in 58ff3ef GAMS runs
• in 7cc8a8b (identical with main) GAMS fails
  Both use the same GAMS version and license.
  I suspect, the reason GAMS fails after refactoring is a change in paths (so GAMS is unable to find scenario.run).
  E.g. in /home/runner/work/xl2times/xl2times/xl2times/benchmarks/out/DemoS_001-all/scenario.run, the out subfolder looks new to me...

[siddharth-krishna]

Thanks, Olex, this is great detective work! (I tried to look for a last commit where gams ran successfully and couldn't find one, I must have missed something...) Looks like my CI refactor moved the TIMES_model path to inside the xl2times root folder, but this is something that probably makes sense for local developers (to keep all xl2times-related stuff within the root folder) so I've modified the CI to also use that path. This fixes gams for Demos & Ireland 🚀

We still have some errors on NZ:

• One issue is because we expect a file ts.dd in the ground truth, but NZ has it as e.g. TIMES-NZ-GAMS/times_scenarios/kea-v2_1_3/kea-v2_1_3_ts.dd. What's a nice way to resolve this, should we add a field to benchmarks.yml specifying the name of the TS file?
• The other was because there was a redundant .dd extension in benchmarks.yml for the NZ models, I've fixed this. Now there are a whole host of Domain violation errors, but these can be resolved by fixing the TS path above. Fixing that leads to one more issue:
• There is no milestonyr.dd file in NZ ground truth, they have it manually specified in e.g. kea-v2_1_3.run. Adding this definition makes gams run without errors.

Perhaps we can take advantage of your prescience and add a ts.dd and milestonyr.dd to your branch of the NZ model repo? :)

[olejandro]

@siddharth-krishna seems ready now!