plotly: Add missing cast to str for rich.Text conversion.

DVC passes some values as `rich.Text` instead of string.
As an oversight in #69 , the refactor to use `list_dict_to_dict_list` removed this string casting, breaking `dvc exp show --pcp`

src/dvc_render/plotly.py

@@ -50,6 +50,7 @@ def _get_plotly_data(self):
 
         trace: Dict[str, Any] = {"type": "parcoords", "dimensions": []}
         for label, values in tabular_dict.items():
+            values = list(map(str, values))
             is_categorical = False
             try:
                 float_values = [

tests/test_parallel_coordinates.py

@@ -3,7 +3,7 @@
 from dvc_render.html import render_html
 from dvc_render.plotly import ParallelCoordinatesRenderer
 
-# pylint: disable=missing-function-docstring, unspecified-encoding
+# pylint: disable=C0116, W1514, W0212, R0903
 
 
 def expected_format(result):
@@ -170,3 +170,15 @@ def test_fill_value():
         "label": "scalar",
         "values": [None, 2.0],
     }
+
+
+def test_str_cast():
+    class Foo:
+        def __str__(self):
+            return "1"
+
+    datapoints = [{"foo": Foo()}]
+    renderer = ParallelCoordinatesRenderer(datapoints, fill_value="-")
+
+    result = renderer._get_plotly_data()
+    assert result["data"][0]["dimensions"][0]["values"] == [1.0]