新增：合并请求关联疑修逻辑

app/models/pull_request.rb

@@ -44,6 +44,8 @@ class PullRequest < ApplicationRecord
   has_many :pull_requests_reviewers, dependent: :destroy
   has_many :reviewers, through: :pull_requests_reviewers
   has_many :mark_files, dependent: :destroy
+  has_many :pull_attached_issues, dependent: :destroy 
+  has_many :attached_issues, through: :pull_attached_issues, source: :issue
 
   scope :merged_and_closed, ->{where.not(status: 0)}
   scope :opening, -> {where(status: 0)}