Fix graphviz file header

The two header comments were missing an endline.

Closes #258

src/wireviz/Harness.py

@@ -93,8 +93,8 @@ def connect(self, from_name: str, from_pin: (int, str), via_name: str, via_wire:
 
     def create_graph(self) -> Graph:
         dot = Graph()
-        dot.body.append(f'// Graph generated by {APP_NAME} {__version__}')
-        dot.body.append(f'// {APP_URL}')
+        dot.body.append(f'// Graph generated by {APP_NAME} {__version__}\n')
+        dot.body.append(f'// {APP_URL}\n')
         dot.attr('graph', rankdir='LR',
                  ranksep='2',
                  bgcolor=wv_colors.translate_color(self.options.bgcolor, "HEX"),