Update related_website_sets.JSON

[grupolpg]

Adds laprensagrafica, elgrafico.com, eleconomista.net, ellas.sv and grupolpg.sv as related sites

[google-cla]

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[github-actions]

It appears you have failed some tests. Here are your results:
There was an error when loading pull-request/related_website_sets.JSON;
error was: Expecting property name enclosed in double quotes: line 672 column 5 (char 27723)