Update index.md

Author: patrick-rodgers

docs/file-handlers/index.md

@@ -139,7 +139,6 @@ You can see an example of using a data model object and handler method for cachi
 
 ### File Handler example solutions
 
-- [GPXFileHandler](https://github.com/OfficeDev/GPX-FileHandler)
 - [markdown-file-handler (C#)](https://github.com/rgregg/o365-markdown-file-handler)
 - [markdown-file-handler (TypeScript)](https://github.com/pnp/contoso/tree/main/filehandler)