ci: enable update_pcu in label job to test fix

Temporarily enable update_pcu to install pcu from GitHub main branch
to test the fix for the label_next_pr filter bug.

Signed-off-by: Jeremiah Russell <jrussell@jerus.ie>

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Signed-off-by: Jeremiah Russell <jerry@jrussell.ie>

.circleci/config.yml

@@ -52,6 +52,7 @@ workflows:
       - toolkit/label:
           min_rust_version: << pipeline.parameters.min_rust_version >>
           context: pcu-app
+          update_pcu: true
           filters:
             branches:
               only: