squashfs-tools: bump to 4.7.5

squashfs-tools: bump to 4.7.5

Changes since 4.7.2:
- Fix potential corruption in Squashfs filesystems containing sparse files
- Fix pseudo file creation failures with large blocks of contiguous zeros
- Fix duplicate file detection for files exceeding available buffer space
- Add -numeric-owner option to mksquashfs/sqfstar
- Fix segfault when using pseudo file root definitions with only Xattr metadata
- Fix conflict between -offset and -stream options
- Fix directory modification timestamp issues in pseudo file hierarchy
- Fix -max-depth incorrectly marking empty directories as excluded

Full release notes:
https://github.com/plougher/squashfs-tools/releases/tag/4.7.5

Signed-off-by: Alexandru Ardelean <redacted>