ob-maxima-test: Tiny cleanup

* testing/examples/ob-maxima-test.org: Removed superfluous source block
  variable.

testing/examples/ob-maxima-test.org

@@ -73,7 +73,7 @@ print(ms);
   :PROPERTIES:
   :ID:       cc158527-b867-4b1d-8ae0-b8c713a90fd7
   :END:
-#+begin_src maxima :var s=test_tbl_mtr :results silent
+#+begin_src maxima :results silent
 m: genmatrix (lambda([i,j], i+j-1), 3, 3)$
 write_data(m, "/dev/stdout")$
 #+end_src