Bump poetry from 1.1.7 to 1.1.8 in /.github/workflows (#256)

Bumps [poetry](https://github.com/python-poetry/poetry) from 1.1.7 to 1.1.8.
- [Release notes](https://github.com/python-poetry/poetry/releases)
- [Changelog](https://github.com/python-poetry/poetry/blob/1.1.8/CHANGELOG.md)
- [Commits](python-poetry/poetry@1.1.7...1.1.8)

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

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/constraints.txt

@@ -1,5 +1,5 @@
 pip==21.2.4
 nox==2020.12.31
-poetry==1.1.7
+poetry==1.1.8
 virtualenv==20.7.2
 nox-poetry==0.8.6