Add admin notifications for new Mastodon versions (#26582)

app/lib/admin/system_check/software_version_check.rb

@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+class Admin::SystemCheck::SoftwareVersionCheck < Admin::SystemCheck::BaseCheck
+  include RoutingHelper
+
+  def skip?
+    !current_user.can?(:view_devops) || !SoftwareUpdate.check_enabled?
+  end
+
+  def pass?
+    software_updates.empty?
+  end
+
+  def message
+    if software_updates.any?(&:urgent?)
+      Admin::SystemCheck::Message.new(:software_version_critical_check, nil, admin_software_updates_path, true)
+    else
+      Admin::SystemCheck::Message.new(:software_version_patch_check, nil, admin_software_updates_path)
+    end
+  end
+
+  private
+
+  def software_updates
+    @software_updates ||= SoftwareUpdate.pending_to_a.filter { |update| update.urgent? || update.patch_type? }
+  end
+end