EUCLID : include new datalink retrieval types 'SPECTRA_BGS' and 'SPECTRA_RGS'

[cosmoJFH]

Dear Astroquery team,

the Euclid datalink service has been updated, and the new retrieval types 'SPECTRA_BGS', 'SPECTRA_RGS' are now available. We would like to include them in Euclid module, so the method get_spectrum could use them.

cc @esdc-esac-esa-int

jira: EUCLIDPCR-1914

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 69.10%. Comparing base (2dbfa3f) to head (c5b7a81).
Report is 236 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3249      +/-   ##
==========================================
+ Coverage   69.07%   69.10%   +0.02%     
==========================================
  Files         232      232              
  Lines       19617    19632      +15     
==========================================
+ Hits        13551    13566      +15     
  Misses       6066     6066              

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[bsipocz]

Some minor comments, otherwise looks good. I'll just go ahead and commit the suggestions and merge the PR.

Thanks!

[bsipocz]

Apparently, I had a very quick review of the tests in the original PR and didn't notice that a lot of them are catching very generic Exceptions rather than the more specific exception type the code is expected to raise. Ideally, those need to be fixed and be made more specific.

I've also added an example of how to match the error message without a new assert line, etc.

The former would be nice to be addressed sometime in the future, while the latter is just a nice pytest feature but it doesn't matter much if the code is refactored or not.