**Describe the bug** Receiving a 429 from Audio features endpoint will cause a NPE since `Retry-After` header is not present <img width="1089" alt="Screenshot 2024-05-11 at 1 18 02 AM" src="https://github.com/adamint/spotify-web-api-kotlin/assets/9221137/c7603535-9c2a-487d-8d73-ac96e5e78339">
Describe the bug
Receiving a 429 from Audio features endpoint will cause a NPE since
Retry-Afterheader is not present