fix bugs in `brainpy.math.random.truncated_normal`

[chaoming0625]

• fix bugs in brainpy.math.random.truncated_normal
• copy random doc of numpy for better readability

[chaoming0625]

Have changed the algorithm of truncated _normal sampling using methods from

• https://people.sc.fsu.edu/~jburkardt/presentations/truncated_normal.pdf

[chaoming0625]

The truncated_normal is not straightforward to multiply the scale and shift the loc. I have checked the algorithms and confirmed the results using methods in https://people.sc.fsu.edu/~jburkardt/presentations/truncated_normal.pdf

[chaoming0625]

One more thing, I have add the checking for the valid setting of loc, scale, upper, and lower, in order to avoid the incorrent sampling.