Using asdf for development environments

I finally switched from rbenv/chruby and venv to asdf.

asdf is is a version manager for multiple programming languages and tools. It allows you to manage multiple versions of languages such as Ruby, Python and others, as well as tools like PostgreSQL and Redis. It also provides a consistent environment across multiple projects and eliminates the possibility of version conflicts between projects.

https://github.com/asdf-vm/asdf