Update new-deprecations.md

Author: laoneo

migrations/44-50/new-deprecations.md

@@ -10,3 +10,9 @@ All the new deprecations that should be aware of and what you should now be usin
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+#### The item_associations property of the WebApplication class is deprecated
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+File: libraries/src/Application/WebApplication.php
+Replacement: The $item_associations property will be removed with no replacement as it is not used in core anymore.