Fix last min torchscript regression in nfnet changes

Author: rwightman

timm/models/nfnet.py

@@ -445,7 +445,7 @@ def forward_features(self, x):
         x = self.final_act(x)
         return x
 
-    def forward_head(self, x, pre_logits=False):
+    def forward_head(self, x, pre_logits: bool = False):
         return self.head(x, pre_logits=pre_logits) if pre_logits else self.head(x)
 
     def forward(self, x):