openexr: 3.3.5 -> 3.3.8

[paperdigits]

Update OpenEXR to resolve #496657 and #494664

Things done

• Built on platform:
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• Tested, as applicable:
  • NixOS tests in nixos/tests.
  • Package tests at passthru.tests.
  • Tests in lib/tests or pkgs/test for functions and "core" functionality.
• Ran nixpkgs-review on this PR. See nixpkgs-review usage.
• Tested basic functionality of all binary files, usually in ./result/bin/.
• Nixpkgs Release Notes
  • Package update: when the change is major or breaking.
• NixOS Release Notes
  • Module addition: when adding a new NixOS module.
  • Module update: when the change is significant.
• Fits CONTRIBUTING.md, pkgs/README.md, maintainers/README.md and other READMEs.

[github-actions]

This report is automatically generated by the PR / Check / cherry-pick CI workflow.

Some of the commits in this PR require the author's and reviewer's attention.

Please follow the backporting guidelines and cherry-pick with the -x flag.
This requires changes to the unstable master and staging branches first, before backporting them.

Occasionally, commits are not cherry-picked at all, for example when updating minor versions of packages which have already advanced to the next major on unstable.
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If you need to merge this PR despite the warnings, please dismiss this review shortly before merging.

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[github-actions]

The PR's base branch is set to release-25.11, but this PR causes 5264 rebuilds.
It is therefore considered a mass rebuild.
Please change the base branch to the right base branch for your changes (probably staging-25.11).