Adjust removal of rails from example app Gemfile

Rails went with double quotes:
```ruby
gem "rails", "~> 7.0.0.alpha2"
```

and this was causing Bundler to complain:

```
[!] There was an error parsing `Gemfile`:
[!] There was an error parsing `Gemfile-rails-dependencies`: You cannot specify the same gem twice with different version requirements.
You specified: rails (~> 7.0.0.alpha2) and rails (>= 0). Bundler cannot continue.

 #  from /Users/pirj/source/rspec-dev/repos/rspec-rails/Gemfile-rails-dependencies:5
 #  -------------------------------------------
 #  when /master/
 >    gem "rails", :git => "https://github.com/rails/rails.git"
 #    gem "activerecord-deprecated_finders", :git => "https://github.com/rails/activerecord-deprecated_finders.git"
 #  -------------------------------------------
. Bundler cannot continue.

 #  from /Users/pirj/source/rspec-dev/repos/rspec-rails/tmp/example_app/Gemfile:63
 #  -------------------------------------------
 #  eval_gemfile '/Users/pirj/source/rspec-dev/repos/rspec-rails/Gemfile-rspec-dependencies'
 >  eval_gemfile '/Users/pirj/source/rspec-dev/repos/rspec-rails/Gemfile-rails-dependencies'
 #  -------------------------------------------
```

Author: pirj

example_app_generator/generate_app.rb

@@ -18,7 +18,7 @@
 
   # Remove the existing rails version so we can properly use main or other
   # edge branches
-  gsub_file 'Gemfile', /^.*\bgem 'rails.*$/, ''
+  gsub_file 'Gemfile', /^.*\bgem ['"]rails.*$/, ''
   gsub_file "Gemfile", /.*web-console.*/, ''
   gsub_file "Gemfile", /.*debugger.*/, ''
   gsub_file "Gemfile", /.*puma.*/, ''