Update Imath to 3.1.12, openexr 3.3.2

[TodicaIonut]

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PR Description

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• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Improvement (non-breaking change which does not add functionality nor fixes a bug but improves Natron in some way)
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What does this pull request do?

Updated Imath package to the latest stable version (3.1.12).