[Junos] Run black on junos.py

Author: hkam40k

napalm/junos/junos.py

@@ -240,7 +240,7 @@ def _load_candidate(self, filename, config, overwrite):
             with open(filename) as f:
                 try:
                     configuration = etree.parse(f).getroot()
-                    fmt = 'xml'
+                    fmt = "xml"
                 except lxml.etree.XMLSyntaxError:
                     configuration = f.read()