Downgrade doxygen to match Morpheus

[cwharris]

Description

Morpheus documentation won't build with doxygen 1.10.0, but we need MRC and Morpheus doxygen versions to match so cross-repository environments can be solved correctly. This PR downgrades doxygen to the version used by Morpheus.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[codecov]

Codecov Report

Merging #469 (e44cdb3) into branch-24.06 (5a6ae3c) will decrease coverage by 0.06%.
The diff coverage is n/a.

Additional details and impacted files

@@               Coverage Diff                @@
##           branch-24.06     #469      +/-   ##
================================================
- Coverage         73.82%   73.76%   -0.06%     
================================================
  Files               402      402              
  Lines             14402    14403       +1     
  Branches           1130     1130              
================================================
- Hits              10632    10625       -7     
- Misses             3770     3778       +8     

Flag	Coverage Δ
cpp	70.36% <ø> (-0.06%)	⬇️
py	41.86% <ø> (ø)

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see 1 file with indirect coverage changes

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[mdemoret-nv]

/merge