### Godot version

4.1.1

### System information

linux

### Issue description

The `"%+f"` format adds a `+` sign in front of positive numbers. If you try to format `-0.0`, it breaks and displays both a `+` and a `-`.

### Steps to reproduce

```gdscript
@tool
extends EditorScript

func _run() -> void:
    print("%+f" % -0.0)
```

### Minimal reproduction project

see above
p_dst++;
			}
			len++;
			p_src += eat;
			p_src_len -= eat;
		} else {
			if (p_dst) {
				*p_dst = *p_src;
				p_dst++;
			}
			len++;
			p_src++;
			p_src_len--;
		}
	}
	return len;
}
 ::xml_unescape() const {
	 str;
	int l = length();
	int len = _xml_unescape(get_data(), l, nullptr);
	if (len == 0) {
		return ();
	}
	str.resize(len + 1);
	_xml_unescape(get_data(), l, str.ptrw());
	str[len] = 0;
	return str;
}
 ::pad_decimals(int p_digits) const {