updates

Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>

train.py

@@ -123,6 +123,7 @@ def train():
         for p in optimizer.param_groups:
             # lower param count allows more aggressive training settings: i.e. SGD ~0.1 lr0, ~0.9 momentum
             p['lr'] *= 100
+            if p.get('momentum') is not None:  # for SGD but not Adam
                 p['momentum'] *= 0.9
 
         for p in model.parameters():