Update rails 5.2 to 6 (THOR MERGE solution included)

Summary of steps

• gem 'rails', '~> 6.0'
• bundle update rails

• rails app:update
  if you get a merge tool error "Please specify merge tool to THOR_MERGE env." Follow these steops:
  exit the update process
  run: $ THOR_MERGE=code rails app:update (selects vs code as your merge tool)
  run rails app:update
  select 'm' to merge files

• Uncomment defaults in new_framework_defaults_6_0.rb

• Go to new framework_defaults_6_0.rb I suggest to read the comments - there are several new defaults which are recommended to uncomment once you are confident that your app is stable on Rails 6. I did as it was suggested.

• Delete new framework_defaults_6_0.rb when app is tested and working.

src - https://fullstackheroes.com/tutorials/rails/upgrade-to-rails-6/