Use .toBeSymbol when checking if a value is a symbol

import {
  defineExpect,
  not,
  test,
  toBeSymbol,
} from "https://deno.land/x/unitest@$VERSION/mod.ts";

const expect = defineExpect({
  matcherMap: {
    toBeSymbol,
  },
  modifierMap: {
    not,
  },
});

test("passes when value is a symbol", () => {
  expect(Symbol()).toBeSymbol();
  expect(true).not.toBeSymbol();
});