fix: convert paths to strings

app.py

@@ -94,10 +94,10 @@ if __name__ == "__main__":
     metadata_root = pathlib.Path(__file__).parent.joinpath("model_cards")
 
     examples = [
-        ["Formation Energy", metadata_root.joinpath("7206075.cif")],
-        ["Bulk moduli", metadata_root.joinpath("crystals.zip")],
-        ["Metal Nonmetal Classifier", metadata_root.joinpath("metal.csv")],
-        ["Bulk moduli", metadata_root.joinpath("9000046.cif")],
+        ["Formation Energy", str(metadata_root.joinpath("7206075.cif"))],
+        ["Bulk moduli", str(metadata_root.joinpath("crystals.zip"))],
+        ["Metal Nonmetal Classifier", str(metadata_root.joinpath("metal.csv"))],
+        ["Bulk moduli", str(metadata_root.joinpath("9000046.cif"))],
     ]
 
     with open(metadata_root.joinpath("article.md"), "r") as f: