Fix regression in VAE code on old pytorch versions.

comfy/ldm/modules/diffusionmodules/model.py

@@ -91,7 +91,7 @@ def __init__(self, in_channels, with_conv, conv_op=ops.Conv2d, scale_factor=2.0)
 
     def forward(self, x):
         scale_factor = self.scale_factor
-        if not isinstance(scale_factor, tuple):
+        if isinstance(scale_factor, (int, float)):
             scale_factor = (scale_factor,) * (x.ndim - 2)
 
         if x.ndim == 5 and scale_factor[0] > 1.0:
@@ -109,7 +109,7 @@ def forward(self, x):
             else:
                 x = a
         else:
-            x = interpolate_up(x, self.scale_factor)
+            x = interpolate_up(x, scale_factor)
         if self.with_conv:
             x = self.conv(x)
         return x