Added capability to close an issue

api/gitlab_classes.py

@@ -160,6 +160,10 @@ class GitlabIssue:
         """
         return self.git_issue.web_url
 
+    def close(self) -> None:
+        self.git_issue.state_event = 'close'
+        self.git_issue.save()
+
     def __repr__(self) -> str:
         issue_number = self.get_project_issue_id()
         title = self.get_title()