fix: use relative import for types module

Changed 'from ffi.types import' to 'from .types import' since
audio_ffi.mojo is inside the ffi package. Absolute imports from
within a package don't work in Mojo's module system.

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 ffi.types import (
+from .types import (
     MojoMelConfig,
     MojoMelSpectrogram,
     MOJO_AUDIO_SUCCESS,