fix typo

modeling_dcpythia.py

@@ -503,7 +503,7 @@ class DCMHAttention(nn.Module):
                     y[:,:,start:stop] = _o
         else: # inference
             if seqlen == 1: # one-token generation
-                k_mask = mask if self.window_size is None else gen_mask[:, :, :,:self.kv_cache.seq_length
+                k_mask = mask if self.window_size is None else gen_mask[:, :, :,:self.kv_cache.seq_length]
                 if fast_infer:
                     y = self._generate_fast(x, input_pos, q, k, v, k_mask)
                 else: