v1.21.0: Add ability to run app in a subfolder

What’s Changed

• Fix push URLs with a Relative Root (#556) @pglombardo
• Add ability to run app in subfolder (#306) @pglombardo
• Automerge Workflow & Cleanup (#552) @pglombardo

🚀 Features

• Latest Language Strings (#542) @pglombardo
• Change License to Apache 2.0 (#543) @pglombardo

⬆️ Dependencies updates

• ⬆️ Bump puma from 6.0.0 to 6.0.1 in /gemfiles/mysql (#548) @dependabot
• ⬆️ Bump puma from 6.0.0 to 6.0.1 (#547) @dependabot
• ⬆️ Bump sprockets from 4.1.1 to 4.2.0 (#546) @dependabot
• ⬆️ Bump rubocop from 1.40.0 to 1.41.0 (#545) @dependabot
• ⬆️ Bump rollbar from 3.3.2 to 3.3.3 (#544) @dependabot
• ⬆️ Bump sprockets from 4.1.1 to 4.2.0 in /gemfiles/mysql (#550) @dependabot
• ⬆️ Bump rollbar from 3.3.2 to 3.3.3 in /gemfiles/mysql (#549) @dependabot
• ⬆️ Bump rubocop from 1.40.0 to 1.41.0 in /gemfiles/mysql (#551) @dependabot
• ⬆️ Bump date from 3.3.1 to 3.3.3 in /gemfiles/mysql (#541) @dependabot
• ⬆️ Bump date from 3.3.1 to 3.3.3 (#540) @dependabot

👥 List of contributors

@dependabot, @dependabot[bot] and @pglombardo