ITK nightly version update

This commit updates:
  (1) SHA used in CMakeLists.txt to checkout ITK sources
          (InsightSoftwareConsortium/ITK@769981b974)
  (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/abfdfe7/scripts/update_python_version.py

Author: kwrobot

CMakeLists.txt

@@ -74,8 +74,8 @@ if(ITKPythonPackage_SUPERBUILD)
 
   set(ITK_REPOSITORY "https://github.com/InsightSoftwareConsortium/ITK.git")
 
-  # ITK nightly-master 2021-07-12
-  set(ITK_GIT_TAG "8aed68490b")
+  # ITK nightly-master 2021-07-13
+  set(ITK_GIT_TAG "769981b974")
 
   #-----------------------------------------------------------------------------
   # A separate project is used to download ITK, so that it can reused

itkVersion.py

@@ -1,4 +1,4 @@
-VERSION = '5.2.0.dev20210712+198.g8aed68490b'
+VERSION = '5.2.0.dev20210713+204.g769981b974'
 
 def get_versions():
     """Returns versions for the ITK Python package.