OpenImageIO 2.1.11.1

Release 2.1.11.1 (11 Feb 2020)

• Fix build break against OpenEXR 2.2 & 2.3, when OpenEXR was built with
  'autotools' and because of a bug in their build systems, neglected to
  install a certain OpenEXR header. It was fine if you were building
  against an OpenEXR that was built using CMake, which included all the
  headers. #2486

If you aren't in this corner case and haven't had build problems complaining about missing ImfFloatVectorAttribute.h, there's no need to rush to upgrade to this mini-release.