floating point error test fails

test `maths.cog`:

```
PASS: Addition
PASS: Subtraction
PASS: Multiplication
PASS: Division
PASS: Modulus
PASS: Floor
PASS: Ceiling
PASS: Round
PASS: Abs
FAIL: Floating point error
FAIL: Floating point error 2
```

Python does not pass either so I'm not going to prioritize fixing this.

```sh
$ python3 -c "print(0.1 + 0.2 == 0.3, 0.3 * 3 + 0.1 == 1)"
False False
```