Add the missing dependency; add Gemfile groups

.github/workflows/build_site.yml

@@ -41,6 +41,8 @@ jobs:
           ruby-version: "3.3"
           bundler-cache: true
           cache-version: 1
+        env:
+          BUNDLE_WITHOUT: lint
 
         # Not all the gems get installed properly for some reason, and
         # I get errors like:

.github/workflows/rubocop.yml

@@ -35,6 +35,8 @@ jobs:
           ruby-version: "3.3"
           bundler-cache: true
           cache-version: 0
+        env:
+          BUNDLE_WITHOUT: build
 
       - name: Run rubocop
         run: bundle exec rubocop

.github/workflows/run_plugin_tests.yml

@@ -33,6 +33,8 @@ jobs:
           ruby-version: "3.3"
           bundler-cache: true
           cache-version: 1
+        env:
+          BUNDLE_WITHOUT: lint
 
         # nokogiri doesn't get installed properly for some reason, and
         # I get errors like:

Gemfile

@@ -1,11 +1,24 @@
 source 'https://rubygems.org'
 
-gem 'chunky_png', '~> 1.4'
-gem 'color', '~> 1.8'
-gem 'html-proofer', '~> 5'
-gem 'jekyll', '~> 4'
-gem 'jekyll-include-cache', '~> 0.2'
-gem 'json-schema', '~> 4'
-gem 'nokogiri', '~> 1.16'
-gem 'rubocop', '~> 1.63'
-gem 'shell-executer', '~> 1.0'
+group :build do
+  gem 'chunky_png', '~> 1.4'
+  gem 'color', '~> 1.8'
+  gem 'html-proofer', '~> 5'
+  gem 'jekyll', '~> 4'
+  gem 'jekyll-include-cache', '~> 0.2'
+  gem 'json-schema', '~> 4'
+  gem 'nokogiri', '~> 1.16'
+  gem 'shell-executer', '~> 1.0'
+end
+
+group :lint do
+  gem 'rubocop', '~> 1.63'
+
+  # This dependency is specifically for CI in GitHub Actions; I don't
+  # need it when I'm running locally.  If I try to run `bundle exec rubocop`
+  # in CI without it, I get an error:
+  #
+  #     cannot load such file -- rubocop-minitest
+  #
+  gem 'rubocop-minitest', '~> 0.35.0'
+end

Gemfile.lock

@@ -125,6 +125,9 @@ GEM
       unicode-display_width (>= 2.4.0, < 3.0)
     rubocop-ast (1.31.2)
       parser (>= 3.3.0.4)
+    rubocop-minitest (0.35.0)
+      rubocop (>= 1.61, < 2.0)
+      rubocop-ast (>= 1.31.1, < 2.0)
     ruby-progressbar (1.13.0)
     ruby-rc4 (0.1.5)
     ruby2_keywords (0.0.5)
@@ -159,6 +162,7 @@ DEPENDENCIES
   json-schema (~> 4)
   nokogiri (~> 1.16)
   rubocop (~> 1.63)
+  rubocop-minitest (~> 0.35.0)
   shell-executer (~> 1.0)
 
 BUNDLED WITH