Fix inferring datetime when no geometry is present

stac_table.py

@@ -155,7 +155,10 @@ def generate(
         or infer_datetime != InferDatetimeOptions.no
         or proj is True
     ):
-        data = dask_geopandas.read_parquet(uri, storage_options=storage_options)
+        if proj:
+            data = dask_geopandas.read_parquet(uri, storage_options=storage_options)
+        else:
+            data = dask.dataframe.read_parquet(uri, storage_options=storage_options)
     #     # TODO: this doesn't actually work
     #     data = dask_geopandas.read_parquet(
     #         ds.files, storage_options={"filesystem": ds.filesystem}

test_stac_table.py

@@ -51,11 +51,11 @@ def test_generate_item(self, partition):
         )
 
         expected_columns = [
-            {"name": "pop_est", "type": "int64"},
+            {"name": "pop_est", "type": "double"},
             {"name": "continent", "type": "byte_array"},
             {"name": "name", "type": "byte_array"},
             {"name": "iso_a3", "type": "byte_array"},
-            {"name": "gdp_md_est", "type": "double"},
+            {"name": "gdp_md_est", "type": "int64"},
             {"name": "geometry", "type": "byte_array"},
         ]
         assert result.properties["table:columns"] == expected_columns
@@ -146,6 +146,20 @@ def test_infer_datetime_range(self):
         assert result.properties["start_datetime"] == "2000-01-01T00:00:00Z"
         assert result.properties["end_datetime"] == "2000-01-03T00:00:00Z"
 
+    def test_infer_datetime_nogeom(self):
+        df = pd.DataFrame(
+            {"A": [pd.Timestamp("2000-01-01"), pd.Timestamp("2000-01-03")]},
+        )
+        df.to_parquet("data.parquet")
+        item = pystac.Item(
+            "naturalearth_lowres", None, None, datetime.datetime(2021, 1, 1), {}
+        )
+        result = stac_table.generate(
+            "data.parquet", item, datetime_column="A", infer_datetime="midpoint",
+            proj=False
+        )
+        assert result.properties["datetime"] == "2021-01-01T00:00:00Z"
+
     def test_metadata(self):
         df = geopandas.GeoDataFrame(
             {"A": [pd.Timestamp("2000-01-01"), pd.Timestamp("2000-01-03")]},