Update quantize_layer.py

Calling super.build() of the layer to indicate that the layer was built.
Previous version did not set the self.built=True flag and would lead to a mismatch between stored and expected weights when loading a .keras model

tensorflow_model_optimization/python/core/quantization/keras/quantize_layer.py

@@ -54,6 +54,7 @@ def __init__(self, quantizer, **kwargs):
     self.quantizer = quantizer
 
   def build(self, input_shape):
+    super(QuantizeLayer, self).build(input_shape)
     if self.quantizer:
       self.quantizer_vars = self.quantizer.build(
           input_shape, self.name, self)