wrong randomness in ou process input

[Newtonpula]

In brainpy._src.inputs.current, the ou_process

def _f(t):
    x.value = x + dt * ((mean - x) / tau) + sigma * dt_sqrt * rng.rand(n)
    return x.value

rng.rand(n) should be rng.randn(n)

[Routhleck]

Thank you for your report! I’ll submit a pull request to address this issue right away.