message: capi: fix typo test message
  PR
diff: @@ -108,7 +108,7 @@ bool test_captures() {
  if (DEBUG) {
  fprintf(stderr,
  "[test_captures] "
  - "expected capture group lenght to be %zd, but "
  + "expected capture group length to be %zd, but "
  "got %zd\n",
  expect_captures_len, captures_len);
  }
  