Log Message:
oxipng: updated to 9.1.4

Version 9.1.4

- [Improvement] Improve optimization of APNG files (reductions still not \ 
supported yet).
- [Improvement] Improve reductions for small images and ensure consistent \ 
results for repeat runs.
- [Build] Add feature `system-libdeflate` to use the system-installed version of \ 
libdeflate.
- [Misc] Strip C2PA metadata by default.