* Bump tj-actions/changed-files from 34 to 35.
* Dev - Bump `codedungeon/phpunit-result-printer` from 0.5.0 to 0.9.3.
* Dev - Bump `node-sass` from 7.0.3 to 8.0.0.
* Dev - Bump `node-wp-i18n` from 1.2.6 to 1.2.7.
* Dev - Bump `phpunit/phpunit` from 6.5.9 to 6.5.14.
* Tweak - Add links to extension requirements on the settings page.
* Add - A new setting to select a Xero Branded Theme template to attach with invoices is introduced.
* Fix - Localization to use 'woocommerce-xero'.
* Fix - Zero tax rate labels not matching issue.
* Tweak - Bump WC tested up to version to 6.7.
* Tweak - Bump minimum PHP version to 7.0.
* Tweak - Bump minimum WC version to 6.0.
* Tweak - Bump minimum WP version to 5.6.
* Tweak - WC 6.8.0 compatibility.
