fix: use new Windows VHD image version

[jackfrancis]

Reason for Change:

This PR updates the Windows VHD reference to version 17763.1339.200718, which will enable new cluster operations with Windows node pools.

Issue Fixed:

Related to #3700

Requirements:

• uses conventional commit messages
• includes documentation
• adds unit tests
• tested upgrade from previous version

Notes:

[acs-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jackfrancis

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[codecov]

Codecov Report

Merging #3701 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #3701   +/-   ##
=======================================
  Coverage   73.15%   73.15%           
=======================================
  Files         147      147           
  Lines       25309    25309           
=======================================
  Hits        18516    18516           
  Misses       5655     5655           
  Partials     1138     1138           

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[mboersma]

InvalidParameter - The following list of images referenced from the deployment template are not found: 
  Publisher: microsoft-aks, Offer: aks-windows, Sku: 2019-datacenter-core-smalldisk-2007, Version: 17763.1339.200718.