v0.8.0

v0.8.0

• updated to latest anari 0.12 SDK
• changed cuda arch detection to use 'native' by default, but allowing
  to override on cmdline.
• updated cuda arch detection in owl and cubql so as to allow barney
  to tell them which one to use (so it matches across all projects)
• reworked path tracing (and in particular MIS code) to (mostly-)pass
  a furnace test