Improve CR3 preview handling (backport #1978)

[mergify]

This is an automatic backport of pull request #1978 done by Mergify.
Cherry-pick of 40e5021 has failed:

On branch mergify/bp/0.27-maintenance/pr-1978
Your branch is up to date with 'origin/0.27-maintenance'.

You are currently cherry-picking commit 40e50215.
  (all conflicts fixed: run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

nothing to commit, working tree clean

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/github/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

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[clanmills]

Right. This looks great. Thanks very much.

[clanmills]

I'll merge this when the CI is green. I'll finish working on the release notes while waiting for the CI. v0.27.5 will be on exiv2.org today for Team Inspection. I'll ask Alex to announce it tomorrow on Facebook and discuss.pixls.us.

[codecov]

Codecov Report

Merging #1981 (5b2fcf7) into 0.27-maintenance (5bfb4d9) will decrease coverage by 0.00%.
The diff coverage is 27.27%.

@@                 Coverage Diff                  @@
##           0.27-maintenance    #1981      +/-   ##
====================================================
- Coverage             46.37%   46.36%   -0.01%     
====================================================
  Files                   146      146              
  Lines                 22988    23005      +17     
  Branches              11806    11809       +3     
====================================================
+ Hits                  10660    10666       +6     
- Misses                 6679     6689      +10     
- Partials               5649     5650       +1     

Impacted Files	Coverage Δ
include/exiv2/bmffimage.hpp	75.00% <ø> (ø)
src/bmffimage.cpp	43.69% <27.27%> (-0.35%)	⬇️

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[kmilos]

Fantastic, thanks!