fix: correct operator precedence in pack_ue8m0_to_int assertion

[kuishou68]

Closes #309

Problem

In deep_gemm/utils/math.py, the pack_ue8m0_to_int function has an operator precedence bug in its assertion:

assert (x.view(torch.int) & ((1 << 23) - 1) == 0).all()

In Python, the == operator has higher precedence than &. So this is actually parsed as:

assert (x.view(torch.int) & (((1 << 23) - 1) == 0)).all()

((1 << 23) - 1) == 0 evaluates to False (i.e., 0), so x.view(torch.int) & 0 produces a tensor of all zeros. .all() on all zeros returns True.

The assertion always passes, never catching cases where mantissa bits are non-zero.

Fix

Added parentheses to ensure & is applied before ==:

assert ((x.view(torch.int) & ((1 << 23) - 1)) == 0).all()

This correctly verifies that the lower 23 mantissa bits are all zero, which is required for valid UE8M0 format floats.