Fix regex warning in bank_account.rb

[arich]

Hi!

I'm getting this error when including this gem in my Rails project.

/Users/arich/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/bundler/gems/lob-ruby/lib/openapi_client/models/bank_account.rb: warning: character class has '-' without escape

Most of the changes here are just consolidating the multiple definitions of the same long regex to a single method. I can undo that if it's not helpful.

The change in detail:
Before:
[a-zA-Z0-9-_]+/

After:
[a-zA-Z0-9\-_]+/

We're just escaping the - as a character you want to include in this regex.

[shayani]

That would be nice. I'm getting tired of seeing this warning every time I run anything on my Rails project.

Is there a way to do not display the warning until this PR is merged?

[mrkaspa]

I created this PR for solving the same #237