feat: retry requests when the api returns a timeout error (#617)

This error code explicitly document that the request should be retried.

Author: jooola

hcloud/_client.py

@@ -129,6 +129,7 @@ class Client:
 
         - ``conflict``
         - ``rate_limit_exceeded``
+        - ``timeout``
 
     Changes to the retry policy might occur between releases, and will not be considered
     breaking changes.
@@ -419,6 +420,7 @@ def _retry_policy(self, exception: APIException) -> bool:
             return exception.code in (
                 "rate_limit_exceeded",
                 "conflict",
+                "timeout",
             )
 
         if isinstance(exception.code, int):