Fixes. 9.3 core

Release 2.3 (https://github.com/ymcatwincities/openy_memberships/releases/tag/2.3) is needed as an intermediate state for the upgrade path.
In order to uninstall swiftmailer - upgrade to the 2.3 release and uninstall the module from your Drupal.
Once uninstalled - proceed with upgrading to the 2.4 version of Open Y Memberships

What's Changed

• PRODDEV-483: Updated styles for modal content by @szherebchuk in #83
• PRODDEV-483: Updated styles by @szherebchuk in #84
• [RGTC-2081] Add “Free Trial” button by @shuklina in #85
• Backport from YN by @podarok in #86
• PRODDEV-473: Updated text if content body is empty by @szherebchuk in #87
• PRODDEV-473: Small fix for modal window by @szherebchuk in #88
• Proddev 475 by @szherebchuk in #89
• PRODDEV-475: Updated styles and fixed problems with styles on mobile by @szherebchuk in #90
• fix: Symfony mailer - allow 9.3 core by @podarok in #92

Full Changelog: 2.2...2.4