Bug#1018013: src:ilmbase will be removed

[Mathieu Malaterre]

Source: nvidia-texture-tools
Version: 2.0.8-1+dfsg-8.2
Severity: serious

I am planning to remove ilmbase now that openexr 3.1.5 has migrated to
testing. Please replace dependency from  libilmbase-dev into
libimath-dev. There should not be any other difference.