Fix CITATION.cff and add automatic validation of your citation metadata (#3320)

* Update CITATION.cff cffversion to 1.2.0

* Fix CITATION.cff date-released

Co-authored-by: Abel Soares Siqueira <abel.s.siqueira@gmail.com>

CITATION.cff

@@ -1,6 +1,6 @@
-cff-version: 1.1.0
+cff-version: 1.2.0
 message: "If you use this software, please cite it as below."
-authors: 
+authors:
   - family-names: Lohmann
     given-names: Niels
     orcid: https://orcid.org/0000-0001-9037-795X
@@ -8,7 +8,7 @@ authors:
     website: https://nlohmann.me
 title: "JSON for Modern C++"
 version: 3.10.5
-date-released: 2022
+date-released: 2022-01-03
 license: MIT
 repository-code: "https://github.com/nlohmann"
 url: https://json.nlohmann.me