update: lamb optimizer

Author: kozistr

pytorch_optimizer/__init__.py

@@ -9,6 +9,7 @@
 from pytorch_optimizer.diffrgrad import DiffRGrad
 from pytorch_optimizer.fp16 import DynamicLossScaler, SafeFP16Optimizer
 from pytorch_optimizer.gc import centralize_gradient
+from pytorch_optimizer.lamb import Lamb
 from pytorch_optimizer.lookahead import Lookahead
 from pytorch_optimizer.madgrad import MADGRAD
 from pytorch_optimizer.optimizers import load_optimizers