Minor: Puzzle 9 does not need N1 as an input

[shenoynikhil]

In Puzzle 9: Long sum, there is no mention of N1 while the function takes as input N1 and T. I think this is a typo and N1 can be safely removed. I tested my solution removing N1 from the function and it seemed to work.

For context, the problem statement

## Puzzle 7: Long Sum

Sum of a batch of numbers.

Uses one program blocks. Block size `B0` represents a range of batches of  `x` of length `N0`.
Each element is of length `T`. Process it `B1 < T` elements at a time.  

and the suggested change:

# before: def sum_kernel(x_ptr, z_ptr, N0, N1, T, B0: tl.constexpr, B1: tl.constexpr):
def sum_spec(x: Float32[Tensor, "4 200"]) -> Float32[Tensor, "4"]:
    return x.sum(1)

@triton.jit
def sum_kernel(x_ptr, z_ptr, N0, T, B0: tl.constexpr, B1: tl.constexpr):
    # TODO: add implementation
    return

# before: test(sum_kernel, sum_spec, B={"B0": 1, "B1": 32}, nelem={"N0": 4, "N1": 32, "T": 200})
test(sum_kernel, sum_spec, B={"B0": 1, "B1": 32}, nelem={"N0": 4, "T": 200})