Fix rand_in_circle uniformity.

[Rapen765]

Enhancement request:

The rand_in_circle function defined in math.py makes more points near the circles's center.

What should be added/changed?

Modify the code code calculating radius r:

# random radius
r = radius * random.random()

to this:

# random radius
r = radius * math.sqrt(random.random())

The square root of a random number ensures the correct density ( based on https://stackoverflow.com/a/50746409 ).

What would it help with?

This change would improve the distribution of points for games that rely on this function, such as when spawning entities within a circle. A more uniform spread can enhance gameplay balance by avoiding the clustering of entities near the center.