Bump minimum Ruby version from 2.3 to 2.5.0 (drop Ruby 2.3 and 2.4 support)
Align with TargetRubyVersion: 2.7
in .rubocop.yml
.
Also you do not have to support Ruby 2.3 and 2.4 in 2022.
Signed-off-by: Takuya Noguchi takninnovationresearch@gmail.com