Ambiguous call in sdl2.nim
Hello!
I'm trying to compile the following code for Windows.
(Nim Compiler Version 0.18.1 [Windows: amd64])

> nim cpp --nilseqs:on -r main.nim

```
import nico

proc game_init() =
    echo "init"

proc game_update(dt: Pfloat) = 
    # echo "update: ", dt
    discard

proc game_draw() =
    cls()
    setColor(7)
    print("hello world", 42, 60)

nico.init("test", "test_game")

nico.createWindow("test_game", 128, 128, 4)

nico.run(game_init, game_update, game_draw)
```

I get an error:

> C:\Users\Erik\.nimble\pkgs\nico-0.1.0\nico\backends\sdl2.nim(1134, 16) Error: ambiguous call; both system.$(x: int)[declared in lib\system.nim(1864, 5)] and system.$(x: uint64)[declared in lib\system\strmantle.nim(282, 5)] match for: (uint8)
