fix: suppress JSONDtypeWarning in _get_display_df_and_blob_cols

Author: shuoweil

bigframes/dataframe.py

@@ -813,11 +813,13 @@ def _get_display_df_and_blob_cols(self) -> tuple[DataFrame, list[str]]:
         df = self
         blob_cols = []
         if bigframes.options.display.blob_display:
-            blob_cols = [
-                series_name
-                for series_name, series in self.items()
-                if series.dtype == bigframes.dtypes.OBJ_REF_DTYPE
-            ]
+            with warnings.catch_warnings():
+                warnings.simplefilter("ignore", bigframes.exceptions.JSONDtypeWarning)
+                blob_cols = [
+                    series_name
+                    for series_name, series in self.items()
+                    if series.dtype == bigframes.dtypes.OBJ_REF_DTYPE
+                ]
             if blob_cols:
                 df = self.copy()
                 for col in blob_cols: