JS: Add change note

Author: Napalys

javascript/ql/lib/change-notes/2025-09-15-promisifications.md

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+---
+category: minorAnalysis
+---
+* Added modeling for promisification libraries `@gar/promisify`, `es6-promisify`, `util.promisify`, `thenify-all`, `call-me-maybe`, `@google-cloud/promisify`, and `util-promisify`.
+* Data flow is now tracked through promisified user-defined functions.