fix if/elif branching otherwise bools get diffed twice

Author: Chris Hamill

deepdiff/diff.py

@@ -1534,7 +1534,7 @@ def _diff(self, level, parents_ids=frozenset(), _original_type=None, local_tree=
         if isinstance(level.t1, booleans):
             self._diff_booleans(level, local_tree=local_tree)
 
-        if isinstance(level.t1, strings):
+        elif isinstance(level.t1, strings):
             self._diff_str(level, local_tree=local_tree)
 
         elif isinstance(level.t1, datetimes):