Merge branch 'update-ext-solr-to-7-5-0' into 'develop'

Update EXT:solr to 7.5.0

Closes #282

See merge request !278
3 jobs for develop in 7 minutes and 40 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
passed #5041
build

00:01:12

 
  Layout
passed #5042
layout

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  Deploy
passed #5043
deploy-develop

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