Handle FutureWarning: Downcasting behavior in replace is deprecated

Previously this warning happened:

FutureWarning: Downcasting behavior in `replace` is deprecated and will be removed in a future version. To retain the old behavior, explicitly call `result.infer_objects(copy=False)`. To opt-in to the future behavior, set `pd.set_option('future.no_silent_downcasting', True)`
  df.replace("", np.nan, inplace=True)

setting the option stops Pandas from even trying to downcast (so it no longer has anything to warn about). I then force the downcast explicitly with infer_objects to ensure that the behaviour remains what it was, but not sure this is what I want here.

src/sssom/util.py

@@ -165,7 +165,15 @@ def from_mapping_set_document(cls, doc: MappingSetDocument) -> "MappingSetDataFr
             # For pandas < 2.0.0, call 'infer_objects()' without any parameters
             df = df.infer_objects()
         # remove columns where all values are blank.
+
+        # Context https://github.com/pandas-dev/pandas/issues/57734
+        try:
+            pd.set_option("future.no_silent_downcasting", True)
+        except KeyError:
+            # Option does not exist in this version of pandas
+            pass
         df.replace("", np.nan, inplace=True)
+        df.infer_objects(copy=False)
         df.dropna(axis=1, how="all", inplace=True)  # remove columns with all row = 'None'-s.
 
         slots = _get_sssom_schema_object().dict["slots"]