Update to Bullet v6.1.0 for Ruby 2.7

See https://github.com/flyerhzm/bullet/blob/master/CHANGELOG.md.

Gemfile

@@ -350,7 +350,7 @@ group :development do
 end
 
 group :development, :test do
-  gem 'bullet', '~> 6.0.2'
+  gem 'bullet', '~> 6.1.0'
   gem 'pry-byebug', '~> 3.5.1', platform: :mri
   gem 'pry-rails', '~> 0.3.9'
 

Gemfile.lock

@@ -145,7 +145,7 @@ GEM
     brakeman (4.2.1)
     browser (4.2.0)
     builder (3.2.4)
-    bullet (6.0.2)
+    bullet (6.1.0)
       activesupport (>= 3.0.0)
       uniform_notifier (~> 1.11)
     bundler-audit (0.6.1)
@@ -1245,7 +1245,7 @@ DEPENDENCIES
   bootstrap_form (~> 4.2.0)
   brakeman (~> 4.2)
   browser (~> 4.2)
-  bullet (~> 6.0.2)
+  bullet (~> 6.1.0)
   bundler-audit (~> 0.6.1)
   capybara (~> 3.33.0)
   capybara-screenshot (~> 1.0.22)