`UVec` min/max operations require `Int8` capability in SPIR-V

[LegNeato]

When using min() or max() methods on UVec types (UVec2, UVec3, UVec4)
in rust-gpu, the SPIR-V compiler emits an error requiring the Int8
capability:

  error: Missing required capabilities for types
    |
    = note: i8 type used without OpCapability Int8

Minimal reproduction:

use spirv_std::glam::UVec4;

let uv4 = UVec4::new(1, 2, 3, 4);
let result = uv4.min(UVec4::new(4, 3, 2, 1)); // Triggers Int8
requirement

Workaround:

Manual component-wise comparison works without requiring Int8:

  let min_x = if uv4.x < other.x { uv4.x } else { other.x };

Expected behavior:

UVec min/max operations should work without requiring the Int8
capability, as the vectors contain u32 values.

Environment:

• rust-gpu version: master
• glam version: via spirv-std

This appears to be an issue with how glam's min/max methods are
implemented for SPIR-V targets, possibly using i8 internally for
comparison operations.

[Firestar99]

Duplicate to #147

[LegNeato]

Oh duh, I knew that. Thanks!