fix(python SDKError): Fixed SDKError __str__ (#1480) (#1486)

Co-authored-by: syvokobylka <[email protected]>

Author: drstrangelooker

python/looker_sdk/error.py

@@ -82,7 +82,7 @@ def __str__(self):
     documentation_url: {self.documentation_url}
     error_doc_url:     {self.error_doc_url}
     error details:
-    {sep.join(self.errors)}
+    {sep.join(str(error) for error in self.errors)}
     """