ITK nightly version update

This commit updates:
  (1) SHA used in CMakeLists.txt to checkout ITK sources
          (InsightSoftwareConsortium/ITK@55c170d8a4)
  (2) VERSION variable set in itkVersion.py

It was automatically generated by the script update_python_version.sh [1]

[1] https://github.com/InsightSoftwareConsortium/ITKPythonPackage/blob/4130854/scripts/update_python_version.py

Author: kwrobot

CMakeLists.txt

@@ -94,7 +94,7 @@ if(ITKPythonPackage_SUPERBUILD)
   set(ITK_REPOSITORY "https://github.com/InsightSoftwareConsortium/ITK.git")
 
   # ITK nightly-master 2022-04-27
-  set(ITK_GIT_TAG "ad9ffe28a6")
+  set(ITK_GIT_TAG "55c170d8a4")
 
   #-----------------------------------------------------------------------------
   # A separate project is used to download ITK, so that it can reused

itkVersion.py

@@ -1,4 +1,4 @@
-VERSION = '5.3rc03.dev20220427+370.gad9ffe28a6'
+VERSION = '5.3rc03.dev20220427+374.g55c170d8a4'
 
 def get_versions():
     """Returns versions for the ITK Python package.