Rubocop dependency update to make VSC extension play well with it

The current gemspec rubocop dependency is set to `~> 1.32.0` locking rubocop to a version which has been released on July 21, 2022.
Any plans to relax the dependency specification to perhaps `'>= 1.56.0'`?

The real problem for us is that the [official VSC extension for Rubocop](https://marketplace.visualstudio.com/items?itemName=rubocop.vscode-rubocop) requires at least version 1.53.0 of rubocop:
```
[client] Version reported by `bundle exec rubocop -v`: 1.32.0 (>= 1.53.0 required)
```
otherwise it doesn't work and we miss the chance to have Rubocop running directly in the IDE.