Introduce automated deploy to WP.org

Ported from 10up's GitHub Action: https://github.com/10up/actions-wordpress/blob/598b1572d5024340f09d7efc083a65ebff3bcdef/dotorg-plugin-deploy/entrypoint.sh

README.md

@@ -4,7 +4,7 @@
 **Tags:** view all, pages, paged, paged post, multipage, single view, single page, wp_link_pages, nextpage, next page, quicktag  
 **Requires at least:** 3.2.1  
 **Tested up to:** 5.1  
-**Stable tag:** 0.9.1  
+**Stable tag:** 0.9.2  
 **License:** GPLv2 or later  
 **License URI:** http://www.gnu.org/licenses/gpl-2.0.html  
 
@@ -52,6 +52,7 @@ This plugin is known to conflict with certain plugins, many pertaining to SEO an
 ## Changelog ##
 
 ### 0.9.2 ###
+* Compatible with PHP 7.3
 * Introduce PHPCS tests
 * Update plugin based on PHPCS results