Add CITATION.cff file (python-poetry#8510)

Co-authored-by: Randy Döring <[email protected]>

CITATION.cff

@@ -0,0 +1,21 @@
+cff-version: 1.2.0
+title: "Poetry: Python packaging and dependency management made easy"
+message: >-
+  If you use this software, please cite it using the
+  metadata from this file.
+authors:
+  - family-names: Eustace
+    given-names: Sébastien
+  - name: "The Poetry contributors"
+abstract:  >-
+  Poetry helps you declare, manage and install dependencies of Python projects, ensuring you have the right stack everywhere.
+  Poetry replaces setup.py, requirements.txt, setup.cfg, MANIFEST.in and Pipfile with a simple pyproject.toml based project format.
+license: MIT
+license-url: "https://github.com/python-poetry/poetry/blob/master/LICENSE"
+repository-code: "https://github.com/python-poetry/poetry"
+keywords:
+  - python
+  - packaging
+  - dependency management
+type: software
+url: "https://python-poetry.org"