Fix leak in test_util.c

AddressSanitizer found a leak in test_util_decompress_dos_impl().
Fixes bug #23691.

src/test/test_util.c

@@ -2578,6 +2578,7 @@ test_util_decompress_dos_impl(compress_method_t method)
 
  done:
   teardown_capture_of_logs();
+  tor_free(input);
   tor_free(result);
   tor_free(result2);
 }