Floating inputs for round() should return a Floating output when ndigit is 0

[faze-geek]

On main -

>>> round(12.3,0)
12
>>> round(12.7,0)
13

On branch -

# This is inline with cpython
>>> round(12.3,0)
12.0
>>> round(12.7,0)
13.0
>>> round(-12.7,0)
-13.0
>>> round(-12.3,0)
-12.0

[faze-geek]

Ideally negative ndigit should also behave differently (in pocketpy an error message is returned). I'm not sure if it is intended due to performance, so I have not modified it.
Python -

>>> round(123.45,-1)
120.0
>>> round(123.45,-2)
100.0

[blueloveTH]

If is_int(args[0]), round should return it directly.

>>> round(1123,0)
1123
>>> round(1123,2)
1123
>>> round(1123,214)
1123