refactor: fully remove callback support

BREAKING CHANGES:
- support for callbacks in `getInfo` and `getBasicInfo` has been
  removed, use promises or async/await

lib/info.js

@@ -308,28 +308,10 @@ for (let fnName of ['getBasicInfo', 'getInfo']) {
   /**
    * @param {string} link
    * @param {Object} options
-   * @param {Function(Error, Object)} callback
    * @returns {Promise<Object>}
    */
   const fn = exports[fnName];
-  exports[fnName] = (link, options, callback) => {
-    if (typeof options === 'function') {
-      callback = options;
-      options = {};
-    } else if (!options) {
-      options = {};
-    }
-
-    if (callback) {
-      // TODO: Fully remove callback support in a future release.
-      // eslint-disable-next-line no-console
-      console.warn(
-        `Calling \`ytdl.${fnName}\` with a callback will be removed in a near future release. ` +
-        `Use async/await.`);
-      return exports[fnName](link, options)
-        .then(info => callback(null, info), callback);
-    }
-
+  exports[fnName] = (link, options = {}) => {
     let id = util.getVideoID(link);
     const key = [fnName, id, options.lang].join('-');
     return exports.cache.getOrSet(key, () => fn(id, options));

package.json

@@ -46,7 +46,6 @@
     "dtslint": "^3.6.14",
     "eslint": "^6.8.0",
     "mocha": "^7.0.0",
-    "muk-prop": "^2.0.0",
     "muk-require": "^1.2.0",
     "nock": "^12.0.0",
     "nyc": "^15.0.0",

test/info-test.js

@@ -3,8 +3,6 @@ const path = require('path');
 const assert = require('assert-diff');
 const nock = require('./nock');
 const sinon = require('sinon');
-const spy = require('sinon').spy;
-const muk = require('muk-prop');
 
 
 describe('ytdl.getInfo()', () => {
@@ -121,28 +119,6 @@ describe('ytdl.getInfo()', () => {
         assert.strictEqual(info2, info1);
       });
     });
-
-    describe('Using the callback API', () => {
-      it('Retrieves correct metainfo, with a warning', done => {
-        const scope = nock(id, {
-          type: 'vevo',
-          player: true,
-        });
-
-        const warn = spy();
-        muk(console, 'warn', warn);
-        after(muk.restore);
-
-        ytdl.getInfo(id, (err, info) => {
-          assert.ifError(err);
-          scope.done();
-          assert.ok(info.videoDetails.shortDescription.length);
-          assert.strictEqual(info.formats.length, expectedInfo.formats.length);
-          assert.ok(warn.called);
-          done();
-        });
-      });
-    });
   });
 
   describe('From a non-existant video', () => {