Elastalert: Removal of doc_type

[Fmstrat]

Hi,

Log files on production servers are filling up with this when using ES7:

|elastic-stack_elastalert.1.ub7osixty22buo3yvqrvptivd | 2019-10-18T20:36:04.422464393Z     
|elastic-stack_elastalert.1.ub7osixty22buo3yvqrvptivd | 2019-10-18T20:36:04.458761875Z 20:36:04.457Z ERROR elastalert-server:
|elastic-stack_elastalert.1.ub7osixty22buo3yvqrvptivd | 2019-10-18T20:36:04.458803675Z     ProcessController:  WARNING:root:doc_type has been deprecated since elasticsearch version 6 and will be completely removed in 8

I see there is a TODO in the code to remove doc_type (which we are not using in any of our rules but it is still throwing the error), but is there a workaround until then?

[Tavisco]

+1 on this, because it's polluting the output log so badly