misc: update xml storage to check bytes (#36515)

wcs/qommon/xml_storage.py

@@ -30,7 +30,7 @@ class XmlStorableObject(StorableObject):
     def storage_load(cls, fd):
         first_byte = fd.read(1)
         fd.seek(0)
-        if first_byte == '<':
+        if first_byte == b'<':
             return cls.import_from_xml(fd, include_id=True)
         else:
             return StorableObject.storage_load(fd)