fix: add missing just setup to update-dependencies workflow

The weekly dependency update workflow was failing because the
update-project.sh script delegates to just commands but the workflow
never installed just on the runner.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: SimplicityGuy

.github/workflows/update-dependencies.yml

@@ -43,6 +43,9 @@ jobs:
         with:
           python-version: "3.13"
 
+      - name: 🔧 Setup Just
+        uses: extractions/setup-just@f8a3cce218d9f83db3a2ecd90e41ac3de6cdfd9b # v3
+
       - name: 🔧 Configure git
         run: |
           git config --local user.email "github-actions[bot]@users.noreply.github.com"