chore(deps-dev): bump @aws-amplify/backend from 1.15.0 to 1.16.0

Bumps @aws-amplify/backend from 1.15.0 to 1.16.0.

---
updated-dependencies:
- dependency-name: "@aws-amplify/backend"
  dependency-version: 1.16.0
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]