Fix OfficialName for French Guiana to "Guyane française" (#56)

* Initial plan

* Update OfficialName for French Guiana to "Guyane française"

Co-authored-by: tinohager <8215186+tinohager@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: tinohager <8215186+tinohager@users.noreply.github.com>

Author: Copilot

src/Nager.Country/CountryInfos/FrenchGuianaCountryInfo.cs

@@ -11,7 +11,7 @@ public sealed class FrenchGuianaCountryInfo : ICountryInfo
         public string CommonName => "French Guiana";
 
         /// <inheritdoc/>
-        public string OfficialName => "Guiana";
+        public string OfficialName => "Guyane française";
 
         /// <inheritdoc/>
         public string NativeName => "Guyane française";