ITK nightly version update

This commit updates:
  (1) SHA used in CMakeLists.txt to checkout ITK sources
          (InsightSoftwareConsortium/ITK@3ac149f830)
  (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/62c6a2f/scripts/update_python_version.py

Author: kwrobot

CMakeLists.txt

@@ -75,7 +75,7 @@ if(ITKPythonPackage_SUPERBUILD)
   set(ITK_REPOSITORY "https://github.com/InsightSoftwareConsortium/ITK.git")
 
   # ITK nightly-master 2020-11-25
-  set(ITK_GIT_TAG "6cedbbc261")
+  set(ITK_GIT_TAG "3ac149f830")
 
   #-----------------------------------------------------------------------------
   # A separate project is used to download ITK, so that it can reused

itkVersion.py

@@ -1,4 +1,4 @@
-VERSION = '5.1.1.dev20201125+443.g6cedbbc261'
+VERSION = '5.1.2.dev20201125+434.g3ac149f830'
 
 def get_versions():
     """Returns versions for the ITK Python package.