Bump vue from 3.4.15 to 3.4.21 in /gui

Bumps [vue](https://github.com/vuejs/core) from 3.4.15 to 3.4.21.
- [Release notes](https://github.com/vuejs/core/releases)
- [Changelog](https://github.com/vuejs/core/blob/main/CHANGELOG.md)
- [Commits](https://github.com/vuejs/core/compare/v3.4.15...v3.4.21)

---
updated-dependencies:
- dependency-name: vue
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

gui/package.json

@@ -57,7 +57,7 @@
     "qth-locator": "2.1.0",
     "socket.io": "4.7.4",
     "uuid": "^9.0.1",
-    "vue": "3.4.15",
+    "vue": "3.4.21",
     "vue-chartjs": "5.3.0",
     "vuemoji-picker": "0.2.0"
   },
@@ -80,7 +80,7 @@
     "vite-plugin-electron": "0.28.2",
     "vite-plugin-electron-renderer": "0.14.5",
     "vitest": "1.2.2",
-    "vue": "3.4.15",
+    "vue": "3.4.21",
     "vue-tsc": "1.8.27"
   }
 }