diffguard-diff/unified.rs:546,550: u8→u32 cast uses instead of idiomatic

[EffortlessSteven]

Location\n and

Issue\nClippy / pedantic style: the u8→u32 conversion is infallible and should use instead of .\n\n\n\n## Suggested fix\n\n\n## Priority\nLow — functional equivalent, purely a style/nit cleanup.\n