Did you remove the plugins from app.yml as suggested and tried again?
HINT: The plugin 'discourse-post-voting' is now bundled with Discourse and should not be included in your container configuration. Remove the line 'git clone https://github.com/discourse/discourse-post-voting' from your containers/app.yml file, then try again. For more information, see https://meta.discourse.org/t/373574
HINT: The plugin 'discourse-solved' is now bundled with Discourse and should not be included in your container configuration. Remove the line 'git clone https://github.com/discourse/discourse-solved' from your containers/app.yml file, then try again. For more information, see https://meta.discourse.org/t/373574