Add CITATION.cff file (#100)

* Add CITATION.cff file

CITATION.cff

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+# This CITATION.cff file was generated with cffinit.
+# Visit https://bit.ly/cffinit to generate yours today!
+
+cff-version: 1.2.0
+title: FletcherPenaltySolver.jl
+message: >-
+  If you use this software, please cite it using the
+  metadata from this file.
+type: software
+authors:
+  - given-names: Tangi
+    family-names: Migot
+    email: [email protected]
+    orcid: 'https://orcid.org/0000-0001-7729-2513'
+  - given-names: Abel
+    family-names: Siqueira
+    orcid: 'https://orcid.org/0000-0003-4451-281X'
+  - given-names: Dominique
+    family-names: Orban
+    orcid: 'https://orcid.org/0000-0002-8017-7687'
+doi: 10.5281/zenodo.7153564
+date-released: 2022-10-06