Temporary change to upgrade-git-for-windows for testing

This is to test (in #68) that changes to the composite
action, as it is used in `ci.yml`, are immediately reflected.

This commit shall be reverted after testing.

Author: EliahKagan

.github/actions/upgrade-git-for-windows/action.yml

@@ -13,6 +13,9 @@ runs:
   using: composite
 
   steps:
+    - name: Step that shall be removed  # FIXME: Remove this step after testing.
+      run: Write-Output '::notice:: This notice is for testing and shall be removed.'
+      shell: pwsh
     - name: Report version/build of Git in this runner image
       run: git version --build-options
       shell: pwsh