GAIA: new DR4 retrieval_type MCMC_GSP_PHOT for datalink

[cosmoJFH]

Dear Astroquery team,

we would like to add the new datalink retrieval type MCMC_GSP_PHOT for the next Gaia DR4. Note that this change is compatible with the DR3 retrieval type MCMC_GSPPHOT .

cc @esdc-esac-esa-int
jira: C9GACS-1060

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 70.51%. Comparing base (52b94d7) to head (c285462).
⚠️ Report is 6 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3409   +/-   ##
=======================================
  Coverage   70.51%   70.51%           
=======================================
  Files         232      232           
  Lines       19997    19997           
=======================================
  Hits        14100    14100           
  Misses       5897     5897           

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[bsipocz]

Thank you!