[Copilot]

Remove-me-section

Updated vendored libpng to the latest 1.6.54 drop to keep third-party dependencies current.

• Summary

  • Refreshes bundled libpng sources/headers/README/LICENSE to upstream 1.6.54.

• Key Changes

  • 🧩 Sources: replaced third_party/libpng/src C files with 1.6.54 release versions.
  • 📚 Headers: updated public and private headers plus generated pnglibconf.h to match 1.6.54 feature flags.
  • 📄 Docs: refreshed bundled README and LICENSE from the new upstream release.

• Example

  • New version macro exposure:

    /* libpng version 1.6.54 */
    #define PNG_LIBPNG_VER_STRING "1.6.54"

Generic request

• PR name follows the pattern #1234 – issue name
• branch name does not contain '#'
• base branch (master or release/xx) is correct
• PR is linked with the issue
• task status changed to "Code review"
• code follows product standards
• regression tests updated

For release/xx branch

• backmerge to master (or newer release/xx) branch is created

Optional

• unit-tests written
• documentation updated

Backmerge request

• PR name follows the pattern Backmerge: #1234 – issue name
• PR is linked with the issue
• base branch (master or release/xx) is correct
• code contains only backmerge changes

Bump request

• PR name follows the pattern Bump version to ...
• add brackets [ ] for 'skip ci' and put it into the body
• milestone is linked to PR
• all tickets are closed inside the relevant milestone

Original prompt

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This section details on the original issue you should resolve

<issue_title>Update libpng library to latest version</issue_title>
<issue_description>Update libpng library to latest version</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Update libpng library to latest version #3462

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