Solution to bundler requires Ruby version ＞= 2.3.0
The error is as follows:
An error was reported during the installation of bundler;
ERROR: Error installing bundler: bundler requires Ruby version >= 2.3.0.
View current ruby version
ruby -v # 2.0
1. Install rvm
curl -sSL https://get.rvm.io | bash -s stable
source /usr/local/rvm/scripts/rvm
2. Check the known ruby versions in the rvm library
rvm list known
3. Install a ruby version
rvm install 2.6
4. Use a ruby version
rvm use 2.6.6
5. Set default version
rvm remove 2.3.0
already gone
6. Confirm the final version
ruby --version
7. Execute again
gem install bundler
