ENH: revert remove unused cert

This reverts commit 73410cf602c97466619856890da39db820e7cedf.

src/slic3r/GUI/GUI_App.cpp

@@ -2822,6 +2822,10 @@ __retry:
             m_agent->init_log();
         }
 
+        //BBS set cert dir
+        if (m_agent)
+            m_agent->set_cert_file(resources_dir() + "/cert", "slicer_base64.cer");
+
         init_http_extra_header();
 
         if (m_agent) {