Added option to set the dpi of the output

this adds the option 'output_dpi' for the user. This is used to set the 'dpi' of the output, the default is 96 wich is also the default GraphViz default.
https://graphviz.org/docs/attrs/dpi/

src/wireviz/DataClasses.py

@@ -58,6 +58,7 @@ class Options:
     color_mode: ColorMode = "SHORT"
     mini_bom_mode: bool = True
     template_separator: str = "."
+    output_dpi: Optional[float] = 96.0
 
     def __post_init__(self):
         if not self.bgcolor_node:

src/wireviz/Harness.py

@@ -172,6 +172,7 @@ class Harness:
             bgcolor=wv_colors.translate_color(self.options.bgcolor, "HEX"),
             nodesep="0.33",
             fontname=self.options.fontname,
+            dpi = f'{self.options.output_dpi}',
         )
         dot.attr(
             "node",