Bump poetry from 1.5.1 to 1.6.0 in /.github/workflows

Bumps [poetry](https://github.com/python-poetry/poetry) from 1.5.1 to 1.6.0.
- [Release notes](https://github.com/python-poetry/poetry/releases)
- [Changelog](https://github.com/python-poetry/poetry/blob/master/CHANGELOG.md)
- [Commits](python-poetry/poetry@1.5.1...1.6.0)

---
updated-dependencies:
- dependency-name: poetry
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

.github/workflows/poetry-constraint.txt

@@ -1 +1 @@
-poetry==1.5.1
+poetry==1.6.0