Apply suggestions from code review

Co-authored-by: Caleigh Runge-Hottman <crungehottman@users.noreply.github.com>

Author: rbikar

src/pubtools/pulplib/_impl/client_pulp3/client.py

@@ -52,7 +52,7 @@ def __init__(
         self,
         url: str,
         auth: Optional[tuple] = None,
-        cert: Optional[str] = None,
+        cert: Optional[Union[str, Tuple[str, str]]] = None,
         verify: bool = True,
         timeout: Optional[float] = None,
         max_retries: int = 5,

src/pubtools/pulplib/_impl/client_pulp3/retry.py

@@ -26,7 +26,7 @@ def should_retry_request(exception: Exception) -> bool:
     if isinstance(exception, httpx.HTTPStatusError):
         status_code = exception.response.status_code
         # Retry on timeout, rate limiting, and server errors
-        return status_code in (408, 429, 500, 502, 503, 504, 400)
+        return status_code in (408, 429, 500, 502, 503, 504)
 
     if isinstance(exception, (httpx.TimeoutException, httpx.NetworkError)):
         return True