fix: add severity to structured log write (#783)

Author: minherz

samples/snippets/snippets.py

@@ -38,15 +38,15 @@ def write_entry(logger_name):
     logger.log_text("Hello, world!")
 
     # Simple text log with severity.
-    logger.log_text("Goodbye, world!", severity="ERROR")
+    logger.log_text("Goodbye, world!", severity="WARNING")
 
     # Struct log. The struct can be any JSON-serializable dictionary.
     logger.log_struct(
         {
             "name": "King Arthur",
             "quest": "Find the Holy Grail",
             "favorite_color": "Blue",
-        }
+        }, severity="INFO"
     )
 
     print("Wrote logs to {}.".format(logger.name))