Log Message:
oxipng: updated to 9.1.0

Version 9.1.0

- [Improvement] Add `--keep display` equivalent to `--strip safe`.
- [Improvement] Add modified zeng palette sorting method, improving optimization \ 
of indexed images.
- [Improvement] If only one filter is specified, guarantee to only use this one.
- [Improvement] Evaluate low-depth indexed even if low-depth grayscale was \ 
already achieved.
- [Bugfix] Fix battiato palette sorting method not being used if the input was \ 
not already indexed.
- [Bugfix] Fix rare crash caused by a truncated palette.
- [Build] Reduce size of binaries.
- [Build] Add man page generation.
- [Build] Publish deb archives for Linux.
- [Misc] Bump minimum Rust version to 1.74.0.