nonfree/hplip: bump to 3.20.11, adopt Debian patchset
Since this adheres to DFSG and is present in their main/ repository we might be able to put this into Adélie, though it's quite an irritating thing to package. I adopted their patchset in order to fix the millions of things wrong that upstream seems unwilling to tend to.
These patches will be especially useful in the future if we ever want to build the UI components. For now, they just fixup some of the PPD definitions amongst other things.