fix(stable): wx 3.3.2 String-Konkatenation in AboutDialog (wxUniCharRef)

src/slic3r/GUI/AboutDialog.cpp

@@ -294,7 +294,10 @@ AboutDialog::AboutDialog()
                     find_txt += text_list[i][o];
                     count_txt += text_list[i][o];
                 } else {
-                    find_txt += std::string("\n") + text_list[i][o];
+                    // wxString::operator[] yields wxUniCharRef in wx 3.3.2, which has no
+                    // operator+ with std::string — append in two steps (matches dev branch).
+                    find_txt += "\n";
+                    find_txt += text_list[i][o];
                     count_txt = text_list[i][o];
                 }
             }