Avoid using temp_dir for anatric xml config preview

pyzebra/anatric.py

@@ -59,6 +59,9 @@ class AnatricConfig:
     def save_as(self, filename):
         self._tree.write(filename)
 
+    def tostring(self):
+        return ET.tostring(self._tree.getroot(), encoding="unicode")
+
     def _get_attr(self, name, tag, attr):
         elem = self._tree.find(name).find(tag)
         if elem is None:

pyzebra/app/panel_hdf_anatric.py

@@ -389,11 +389,7 @@ def create():
     )
 
     async def update_config():
-        with tempfile.TemporaryDirectory() as temp_dir:
-            temp_file = temp_dir + "/config.xml"
-            config.save_as(temp_file)
-            with open(temp_file) as f_config:
-                output_config.value = f_config.read()
+        output_config.value = config.tostring()
 
     doc.add_periodic_callback(update_config, 1000)