fix(about): update the release codename to Rebuild

The About modal codename is a hand-set literal and still said
1.2.15's 'Just cleaning'; it now matches the 2.0.0 TAG_DETAILS
headline.

cc

crates/qbz-ui/ui/shell/AboutModal.slint

@@ -368,7 +368,7 @@ export component AboutModal inherits Rectangle {
                                         width: 84px;
                                     }
                                     Text {
-                                        text: "Just cleaning";
+                                        text: "Rebuild 破 (You Can (Not) Advance)";
                                         color: Theme.text-secondary;
                                         font-size: 13px;
                                         font-italic: true;