fix future warning for xml.etree

The warning was: FutureWarning: The behavior of this method will change in future versions. Use specific 'len(elem)' or 'elem is not None' test instead.

src/blenderbim/blenderbim/bim/module/drawing/operator.py

@@ -534,7 +534,7 @@ class CreateDrawing(bpy.types.Operator):
         root = etree.fromstring(results)
 
         group = root.find("{http://www.w3.org/2000/svg}g")
-        if not group:
+        if group is None:
             with open(svg_path, "wb") as svg:
                 svg.write(etree.tostring(root))
 

src/blenderbim/blenderbim/bim/module/drawing/svgwriter.py

@@ -160,7 +160,7 @@ class SvgWriter:
     def find_xml_symbol_by_id(self, id):
         tree = ET.parse(self.resource_paths["Symbols"])
         xml_symbol = tree.find(f'.//*[@id="{id}"]')
-        return External(xml_symbol) if xml_symbol else None
+        return External(xml_symbol) if xml_symbol is not None else None
 
     def add_patterns(self):
         path = self.resource_paths["Patterns"]