[BUG FIX] 使用 float64 避免精度误差问题，弃用 CPU 计算，避免拖累性能

Author: hexisyztem

cosyvoice/hifigan/generator.py

@@ -713,8 +713,8 @@ def decode(self, x: torch.Tensor, s: torch.Tensor = torch.zeros(1, 1, 0), finali
     @torch.inference_mode()
     def inference(self, speech_feat: torch.Tensor, finalize: bool = True) -> torch.Tensor:
         # mel->f0 NOTE f0_predictor precision is crucial for causal inference, move self.f0_predictor to cpu if necessary
-        self.f0_predictor.to('cpu')
-        f0 = self.f0_predictor(speech_feat.cpu(), finalize=finalize).to(speech_feat)
+        self.f0_predictor.to(torch.float64)
+        f0 = self.f0_predictor(speech_feat.to(torch.float64), finalize=finalize).to(speech_feat)
         # f0->source
         s = self.f0_upsamp(f0[:, None]).transpose(1, 2)  # bs,n,t
         s, _, _ = self.m_source(s)