add resample module in preprocessing package, refactor demucs_wrapper.py

src/preprocessing/resample.py

@@ -0,0 +1,18 @@
+import librosa
+
+def resample(waveform, org_samplerate, new_samplerate):
+    """
+    Reads a waveform and returns a waveform resampled to samplerate.
+
+    Args:
+        waveform: waveform of the target audio.
+        org_samplerate : original samplerate of the audio.
+        new_samplerate : samplerate to which the audio is to be resampled.
+    """
+
+    try:
+        waveform = librosa.resample(waveform, orig_sr=org_samplerate, target_sr=new_samplerate)
+        return waveform, new_samplerate
+    except Exception as e: 
+        raise RuntimeError(f"Error reasmpling the audio file: {e}")
+