chore: add missing a11y-base direct dependency to dashboard (#9266)

Author: web-padawan

packages/dashboard/package.json

@@ -37,6 +37,7 @@
   ],
   "dependencies": {
     "@open-wc/dedupe-mixin": "^1.3.0",
+    "@vaadin/a11y-base": "25.0.0-alpha1",
     "@vaadin/button": "25.0.0-alpha1",
     "@vaadin/component-base": "25.0.0-alpha1",
     "@vaadin/vaadin-lumo-styles": "25.0.0-alpha1",