Return body on unwanted status codes

[Fank]

This pull request includes changes to improve error handling in the contacts.go file by adding more detailed error information and updating the Error struct in error.go.

Improvements to error handling:

• contacts.go: Added the io package to the import list to enable reading the response body in case of an error.
• contacts.go: Updated the ContactCreate function to read the response body and include it in the error message if the status code is not http.StatusCreated. This provides more context for debugging.

Updates to Error struct:

• error.go: Added a Body field to the Error struct to store the response body when an error occurs, allowing for more detailed error information.