こちらターミナルのエラー文になります。rubyバージョンがherokuに対応していないとのことですが、解決法の具体的な手順を教えていただきたいです。
remote: !
remote: ! The Ruby version you are trying to install does not exist on this stack.
remote: !
remote: ! You are trying to install ruby-2.6.3 on heroku-20.
remote: !
remote: ! Ruby ruby-2.6.3 is present on the following stacks:
remote: !
remote: ! - cedar-14
remote: ! - heroku-16
remote: ! - heroku-18
remote: !
remote: ! Heroku recommends you use the latest supported Ruby version listed here:
remote: ! https://devcenter.heroku.com/articles/ruby-support#supported-runtimes
remote: !
remote: ! For more information on syntax for declaring a Ruby version see:
remote: ! https://devcenter.heroku.com/articles/ruby-versions
remote: !
