Bump ui5-middleware-simpleproxy in /app/travel_processor

Bumps [ui5-middleware-simpleproxy](https://github.com/ui5-community/ui5-ecosystem-showcase/tree/HEAD/packages/ui5-middleware-simpleproxy) from 3.2.15 to 3.2.16.
- [Changelog](https://github.com/ui5-community/ui5-ecosystem-showcase/blob/main/packages/ui5-middleware-simpleproxy/CHANGELOG.md)
- [Commits](https://github.com/ui5-community/ui5-ecosystem-showcase/commits/[email protected]/packages/ui5-middleware-simpleproxy)

---
updated-dependencies:
- dependency-name: ui5-middleware-simpleproxy
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>