chore(release): bump version to 1.2.8 "My QBZ"

Mixtapes & Collections release. Bumps all version references
(Cargo.toml, tauri.conf.json, package.json, snapcraft.yaml, both
Cargo.lock, package-lock.json), adds the 1.2.8 entry to the Flatpak
metainfo, and sets the About modal codename to "My QBZ".

cc

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "qbz-nix",
-  "version": "1.2.7",
+  "version": "1.2.8",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "qbz-nix",
-      "version": "1.2.7",
+      "version": "1.2.8",
       "license": "MIT",
       "dependencies": {
         "@icons-pack/svelte-simple-icons": "^7.2.0",