Use logging levelno instead of levelname. Levelnames can be overridden

See #1443

sentry_sdk/integrations/logging.py

@@ -110,17 +110,25 @@ def _breadcrumb_from_record(record):
     # type: (LogRecord) -> Dict[str, Any]
     return {
         "type": "log",
-        "level": _logging_to_event_level(record.levelname),
+        "level": _logging_to_event_level(record),
         "category": record.name,
         "message": record.message,
         "timestamp": datetime.datetime.utcfromtimestamp(record.created),
         "data": _extra_from_record(record),
     }
 
 
-def _logging_to_event_level(levelname):
-    # type: (str) -> str
-    return {"critical": "fatal"}.get(levelname.lower(), levelname.lower())
+def _logging_to_event_level(record):
+    # type: (LogRecord) -> str
+    default = 'error'
+    return {
+        logging.DEBUG: 'debug',
+        logging.INFO: 'info',
+        logging.WARNING: 'warning',
+        logging.ERROR: 'error',
+        logging.CRITICAL: 'critical',
+        logging.FATAL: 'fatal',  # CRITICAL is same as FATAL
+    }.get(record.levelno, default)
 
 
 COMMON_RECORD_ATTRS = frozenset(
@@ -220,7 +228,7 @@ def _emit(self, record):
 
         hint["log_record"] = record
 
-        event["level"] = _logging_to_event_level(record.levelname)
+        event["level"] = _logging_to_event_level(record)
         event["logger"] = record.name
 
         # Log records from `warnings` module as separate issues