Specification changes / multiple bug fixes

【Contents of fix】
■Changed Facebook OGP setting from old specification (fb:admins) to new specification (fb:app_id).
※Please refer to the following article about how to get “fb:app_id” (application ID).
 How to get fb:app_id required for Facebook OGP setting
■WP5.6 support (compatible with jQuery upgrade)
■【Mac】 Fixed a bug that Japanese and European characters were displayed with different thickness when using some fonts.
■【macOS Big Sur】 Fixed a bug that the YouTube video in the top page header content would not play in Chrome browser.

The following are the files that have been fixed with this update.
【Modified file】
admin/theme-options.php
comments.php
editor-style-02.css
editor-style-03.css
functions/head.php
functions/ogp.php
functions/seo.php
js/jquery.mb.YTPlayer.min.css
js/jquery.mb.YTPlayer.min.js
languages/ja.mo
languages/ja.po
pagebuilder/assets/css/pagebuilder.css
style.css
widget/ad.php
widget/archive_dropdown.php
widget/category_list.php
widget/google_search.php
widget/styled_post_list1.php
widget/tab_post_list.php
widget/work_category.php
widget/work_list.php

【Added files】
js/jquery.easing.1.4.js