vad : free memory allocated for VAD hparams

This commit frees the model hyperparameters allocated for the VAD
context in the `whisper_vad_free` function. Specifically, it deletes the
`encoder_in_channels`, `encoder_out_channels`, and `kernel_sizes` arrays
allocated with `new[]` in the `whisper_vad_init` function.

The motivation for this is to prevent memory leaks when the VAD.

Resolves: #3452

Author: danbev

src/whisper.cpp

@@ -5434,8 +5434,13 @@ void whisper_vad_free(whisper_vad_context * ctx) {
         for (auto & backend : ctx->backends) {
             ggml_backend_free(backend);
         }
+
         ggml_free(ctx->ctx);
 
+        delete[] ctx->model.hparams.encoder_in_channels;
+        delete[] ctx->model.hparams.encoder_out_channels;
+        delete[] ctx->model.hparams.kernel_sizes;
+
         delete ctx;
     }
 }