Use output_name as default title

The CLI handling code was redesigned for v0.4 and it seems the code
to assigned a default title from v0.3.1 has been messed up. This bug
has not been triggered by build_examples.py due to it seems to call
the parse() function differently.

The output_name should be as default title when present.

This will fix the #360 bug report.

src/wireviz/wireviz.py

@@ -117,10 +117,7 @@ def parse(
 
     # When title is not given, either deduce it from filename, or use default text.
     if "title" not in harness.metadata:
-        if yaml_file is None:
-            harness.metadata["title"] = "WireViz diagram and BOM"
-        else:
-            harness.metadata["title"] = Path(yaml_file).stem
+        harness.metadata["title"] = output_name or "WireViz diagram and BOM"
 
     # add items
     # parse YAML input file ====================================================