This package does not include the upstream changelog in
/usr/share/doc/python3-fastapi.  The patch below fixes this.
--- fastapi-0.115.5/debian/rules        2024-11-29 02:00:07.000000000 +0000
+++ fastapi-0.115.5/debian/rules        2025-01-14 20:46:24.000000000 +0000
@@ -35,3 +36,6 @@

 %:
 	dh $@ --with python3 --buildsystem=pybuild
+
+override_dh_installchangelogs:
+	dh_installchangelogs docs/en/docs/release-notes.md



Best wishes,

   Julian