Use CITATION.cff instead of Zenodo metadata

.zenodo.json

-{
-  "title": "OpenMDAO-Bridge-Excel",
-  "description": "<p>An OpenMDAO component for running analyses in Excel.</p><p>More information is available on GitHub and in the README file.</p>",
-  "license": "MIT",
-  "creators": [
-    {
-      "affiliation": "Link\u00f6ping University",
-      "name": "Vidner, Olle",
-      "orcid": "0000-0002-1157-2480"
-    }
-  ]
-}

CITATION.cff

+cff-version: 1.2.0
+message: "If you use this software, please cite it using the metadata supplied in the CITATION.cff file."
+doi: 10.5281/zenodo.4501330
+title: "OpenMDAO-Bridge-Excel"
+authors:
+  - family-names: Vidner
+    given-names: Olle
+    affiliation: Linköping University
+    orcid: https://orcid.org/0000-0002-1157-2480
+license: MIT
+repository-code: https://github.com/ovidner/openmdao-bridge-excel