Java: add change note

Author: Jami Cogswell

java/ql/lib/change-notes/2023-11-29-new-spring-models.md

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+---
+category: minorAnalysis
+---
+* Added a sink model for the `createRelative` method of the `org.springframework.core.io.Resource` interface.
+* Added source models for methods of the `org.springframework.web.util.UrlPathHelper` class and removed their taint flow models.