我正在尝试将我的 Rails 应用程序推送到 Heroku，但它一次又一次地向我显示此错误。问题是什么？
Enumerating objects: 140, done.
Counting objects: 100% (140/140), done.
Delta compression using up to 2 threads
Compressing objects: 100% (122/122), done.
Writing objects: 100% (140/140), 145.92 KiB | 1.50 MiB/s, done.
Total 140 (delta 10), reused 0 (delta 0), pack-reused 0
remote: Compressing source files... done.
remote: Building source:
remote:
remote: -----> Building on the Heroku-20 stack
remote: -----> Determining which buildpack to use for this app
remote: ! Warning: Multiple default buildpacks reported the ability to handle this app. The first buildpack in the list below will be used.
remote: Detected buildpacks: Ruby,Node.js
remote: See https://devcenter.heroku.com/articles/buildpacks#buildpack-detect-order
remote: -----> Ruby app detected
remote: -----> Installing bundler 2.2.21
remote: -----> Removing BUNDLED WITH version in the Gemfile.lock
remote: -----> Compiling Ruby/Rails
remote: Command: 'set -o pipefail; curl -L --fail --retry 5 --retry-delay 1 --connect-timeout 3 --max-time 30 https://s3-external-1.amazonaws.com/heroku-buildpack-ruby/heroku-20/ruby-2.7.0.tgz -s -o - | tar zxf - ' failed on attempt 1 of 3.
remote: Command: 'set -o pipefail; curl -L --fail --retry 5 --retry-delay 1 --connect-timeout 3 --max-time 30 https://s3-external-1.amazonaws.com/heroku-buildpack-ruby/heroku-20/ruby-2.7.0.tgz -s -o - | tar zxf - ' failed on attempt 2 of 3.
remote:
remote: !
remote: ! The Ruby version you are trying to install does not exist on this stack.
remote: !
remote: ! You are trying to install ruby-2.7.0 on heroku-20.
remote: !
remote: ! Ruby ruby-2.7.0 is present on the following stacks:
remote: !
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: !
remote: ! Push rejected, failed to compile Ruby app.
remote:
remote: ! Push failed
remote: Verifying deploy...
remote:
remote: ! Push rejected to first-rails-application11.
remote:
To https://git.heroku.com/first-rails-application11.git
! [remote rejected] dev -> main (pre-receive hook declined)
error: failed to push some refs to 'https://git.heroku.com/first-rails-application11.git'
我跑了heroku loginand heroku create，在完成了一些步骤后，我跑了git push heroku main，得到了这个错误。我也试过 git push heroku main: main了，但这并没有改变任何东西。然后我创建了一个分支，然后例如，dev然后我运行git push heroku dev:main但它再次失败。