Allow testing with specific versions of blacklight

Author: jcoyne

.github/workflows/ruby.yml

@@ -14,7 +14,7 @@ jobs:
         rails_version: ['7.0.4.1']
         ruby: ['3.1', '3.2']
         bootstrap_version: ['~> 4.0']
-        blacklight_version: ['latest']
+        blacklight_version: ['']
         additional_engine_cart_rails_options: ['']
         additional_name: ['']
         include:

spec/test_app_templates/Gemfile.extra

@@ -5,4 +5,6 @@ if ENV['BLACKLIGHT_VERSION'] == 'edge'
   gem 'blacklight', github: 'projectblacklight/blacklight'
   gem 'blacklight-gallery', github: 'projectblacklight/blacklight-gallery'
   gem 'blacklight-oembed', github: 'projectblacklight/blacklight-oembed'
+elsif ENV['BLACKLIGHT_VERSION'] && !ENV['BLACKLIGHT_VERSION'].blank?
+  gem 'blacklight', ENV['BLACKLIGHT_VERSION']
 end