openimageio 1.5.13
openimageio 1.5.13

* Avoids linking to a specific Python framework.
* update tgautils resource
* add test
* add explicit libpng dependency
* hint CMAKE_FIND_FRAMEWORK=LAST
  From std_cmake_args, tell cmake to look for frameworks in /Library only
  after looking for Homebrew-installed libraries.
* add optional giflib dependency

Fixes #1981. Closes #1998.

quantumsteve/homebrew-science,joshbode/homebrew-science,maplesond/homebrew-science,goxberry/homebrew-science,philippbayer/homebrew-science,parcollet/homebrew-science,ahundt/homebrew-science,DabeDotCom/homebrew-science,andrewjpage/homebrew-science,kozo2/homebrew-science,pditommaso/homebrew-science,ge11232002/homebrew-science,aeantipov/homebrew-science,dpo/homebrew-science,heuermh/homebrew-science,pmelsted/homebrew-science