fix: check str(exc) instead of http_response.text for retryable phrases

Author: aliev

tests/base.py

@@ -54,18 +54,11 @@ def _is_retryable_error(exc: Exception) -> bool:
     if isinstance(exc, AssertionError):
         return True
     if isinstance(exc, StreamAPIException):
-        if exc.status_code == 429:
+        if exc.status_code in (429, 502, 503, 504):
             return True
-        if exc.status_code in (502, 503, 504):
-            return True
-        body = ""
-        try:
-            body = exc.http_response.text or ""
-        except Exception:
-            pass
-        lowered = body.lower()
+        msg = str(exc).lower()
         if any(
-            phrase in lowered
+            phrase in msg
             for phrase in (
                 "upstream connect error",
                 "disconnect",