STYLE: Fix SetIn/OutsideValue calls ConnectedComponentImageFilterTestRGB

The `SetInsideValue` and `SetOutsideValue` member functions of
`BinaryThresholdImageFilter<InternalImageType, RGBImageType>` expect an
RGB pixel value as argument, not just a single `unsigned short` value!

Issue found by locally (temporarily) declaring the converting
constructor `RGBPixel(const ComponentType &)` "explicit".

Author: N-Dekker

Modules/Segmentation/ConnectedComponents/test/itkConnectedComponentImageFilterTestRGB.cxx

@@ -71,8 +71,8 @@ itkConnectedComponentImageFilterTestRGB(int argc, char * argv[])
   threshold_hi = std::stoi(argv[4]);
 
   threshold->SetInput(reader->GetOutput());
-  threshold->SetInsideValue(itk::NumericTraits<InternalPixelType>::OneValue());
-  threshold->SetOutsideValue(itk::NumericTraits<InternalPixelType>::ZeroValue());
+  threshold->SetInsideValue(itk::NumericTraits<RGBPixelType>::OneValue());
+  threshold->SetOutsideValue(itk::NumericTraits<RGBPixelType>::ZeroValue());
   threshold->SetLowerThreshold(threshold_low);
   threshold->SetUpperThreshold(threshold_hi);
   threshold->Update();