build: bump promptflow from 1.15.0 to 1.16.0

Bumps [promptflow](https://github.com/microsoft/promptflow) from 1.15.0 to 1.16.0.
- [Release notes](https://github.com/microsoft/promptflow/releases)
- [Commits](microsoft/promptflow@promptflow_1.15.0...promptflow_1.16.0)

---
updated-dependencies:
- dependency-name: promptflow
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

poetry.lock

@@ -56,7 +56,7 @@ pytest-asyncio = "^0.24.0"
 optional = true
 
 [tool.poetry.group.prompt-flow.dependencies]
-promptflow = {extras = ["azure"], version = "1.15.0"}
+promptflow = {extras = ["azure"], version = "1.16.0"}
 
 [tool.coverage.run]
 omit = [