Ignore @metamask/snaps-ui deprecation (#21896)

`@metamask/snaps-ui` is indirectly used by `@metamask/keyring-api` but
is deprecated, so we are getting an audit failure. Replacing
`@metamask/snaps-ui` with `@metamask/snaps-sdk` will solve this but in
the meantime we are ignoring this deprecation to unblock further merges.

.yarnrc.yml

@@ -111,6 +111,11 @@ npmAuditIgnoreAdvisories:
   # remove this.
   - '@metamask/types (deprecation)'
 
+  # @metamask/keyring-api also depends on @metamask/snaps-ui which is
+  # deprecated. Replacing that dependency with @metamask/snaps-sdk will remove
+  # this.
+  - '@metamask/snaps-ui (deprecation)'
+
 npmRegistries:
   'https://npm.pkg.github.com':
     npmAlwaysAuth: true