fix: use direct import for types module (same directory)

Mojo doesn't support relative imports in this context. Since
audio_ffi.mojo and types.mojo are in the same ffi/ directory,
use direct import without package prefix.

Author: itsdevcoffee

src/ffi/audio_ffi.mojo

@@ -21,7 +21,7 @@ from math.constants import pi
 from memory import UnsafePointer
 from memory.unsafe_pointer import alloc
 
-from .types import (
+from types import (
     MojoMelConfig,
     MojoMelSpectrogram,
     MOJO_AUDIO_SUCCESS,