remove deprecated Windows image

.github/workflows/build-windows.yml

@@ -21,8 +21,6 @@ jobs:
         # Github Actions requires a single row to be added to the build matrix.
         # See https://help.github.com/en/articles/workflow-syntax-for-github-actions.
         name: [
-            #TODO This build fails, need to understand why.
-            # windows-2016-cl,
             windows-2019-cl,
           ]
 
@@ -32,12 +30,6 @@ jobs:
           ]
         build_unstable: [ON]
         include:
-          #TODO This build fails, need to understand why.
-          # - name: windows-2016-cl
-          #   os: windows-2016
-          #   compiler: cl
-          #   platform: 32
-
           - name: windows-2019-cl
             os: windows-2019
             compiler: cl