Fix pycpufit issue when passing user_info

[Nikongen]

Fixes #143

Validated using

import numpy as np
import pycpufit.cpufit as gf


def test(n_fits: float = 1e6) -> float:
    n_fits = int(n_fits)
    params = np.random.rand(n_fits, 2).astype(np.float32)

    x = np.random.rand(n_fits, 300).astype(np.float32) * 100
    y = params[:, :1] + params[:, 1:] * x

    init_params = np.array([0.1, 0.1], dtype=np.float32)
    init_params = np.tile(init_params, (n_fits, 1))

    parameters, states, chi_squares, number_iterations, execution_time = gf.fit(
        data=y,
        weights=None,
        model_id=gf.ModelID.LINEAR_1D,
        initial_parameters=init_params,
        tolerance=1e-8,
        user_info=x
        )
    max_error = np.max(abs(params - parameters))
    print(f"\tmean abs error = {np.mean(abs(params - parameters)):2.2e}")
    print(f"\tmax abs error = {max_error:2.2e}")
    print(f"\tHas{"" if np.any(abs(params - parameters) > 1e-3) else ' no'} fit with error > 1e-3")
    return max_error


iters = 2
n_fits = 1700000
max_errors = np.zeros(iters, dtype=float)
for i in range(iters):
    print(f"Test run {i+1:3d}")
    max_errors[i] = test(n_fits)

print(f"Overall max error after : {np.max(max_errors):2.2e}")