Update fennel set_form grammar structure

The fennel grammar was updated to remove binding_pair from set.

alexmozaidze/tree-sitter-fennel@49293d2

Author: micampe

queries/fennel/textobjects.scm

@@ -102,9 +102,8 @@
     rhs: (_) @assignment.rhs) @assignment.inner) @assignment.outer
 
 (set_form
-  (binding_pair
-    lhs: (_) @assignment.lhs
-    rhs: (_) @assignment.rhs) @assignment.inner) @assignment.outer
+  lhs: (_) @assignment.lhs @assignment.inner
+  rhs: (_) @assignment.rhs @assignment.inner) @assignment.outer
 
 (let_vars
   (binding_pair