Warnings about PDF version of logos

The logos were re-written in !11 (merged) , but are now in PDF v1.7 format, so we get this warning on all docs:

warning  (file logos/ctao_dpps.pdf) (pdf inclusion): PDF inclusion: found PDF version '1.7', but at most version '1.5' allowed

Can we either:

1. set the output to be PDF-1.7 (is that less compatible or something?)
2. disable this warning
3. convert the logos to PDF-1.5?

Also, I tried setting \pdfminorversion=7 in docs, but it works for pdflatex, but not for lualatex it seems