Remove duplicate dependency development gem
Remove duplicate dependency development gem

This PR suppress the following warning.

```console
% cd path/to/rubocop
% bundle install
Your Gemfile lists the gem pry (>= 0) more than once.
You should probably keep only one of them.
Remove any duplicate entries and specify the gem only once.
While it's not a problem now, it could cause errors if you change the
version of one of them later.
Using rake 12.3.3
Using public_suffix 4.0.3

(snip)
```

`pry` gem is already in the Gemfile.
This looks like it was accidentally added in #7663.

rrosenblum/rubocop,tejasbubane/rubocop,deivid-rodriguez/rubocop,tdeo/rubocop,jmks/rubocop,maxjacobson/rubocop,maxjacobson/rubocop,deivid-rodriguez/rubocop,deivid-rodriguez/rubocop,tejasbubane/rubocop,tejasbubane/rubocop,jmks/rubocop,rrosenblum/rubocop,tdeo/rubocop,tdeo/rubocop,bbatsov/rubocop,maxjacobson/rubocop,rrosenblum/rubocop,bbatsov/rubocop,jmks/rubocop