Convert to PDF 1.7 - any solution?

I am making books into LibreOffice Draw and I post them online for free, but in order to optimize the PDFs for the web that I export through Draw, I need PDF version 1.7. Draw exports in an old format 1.4 - and yes I have the latest LibreOffice installed. So how to convert a PDF 1.4 to PDF 1.7 or newer?

Right now the only way to do this is through GhostScript which is a bit cumbersome (terminal) or through GV program that looks like it is from the 90s and it is difficult to navigate. Is there a better solution like a simple PDF convertor? If I use Master PDF Editor it works like a charm, but that's proprietary so I am looking for a FOSS alternative.

Thanks