fix(tool/formats): five -> rdr3 embedded textures crash on unload

[Ktos93]

Goal of this PR

Fix crash when models with embedded textures crash on unload

This PR applies to the following area(s)

RedM converter

Successfully tested on

Checklist

• [x] Code compiles and has been tested successfully.
• [x] Code explains itself well and/or is documented.
• [x] My commit message explains what the changes do and what they are for.
• [x] No extra compilation warnings are added by these changes.