fix(run-tck): update TCK repository reference

The a2a-tck repository has been moved from maeste/a2a-tck to a2aproject/a2a-tck.

This commit updates the checkout action in the run-tck.yml workflow to point to the new repository location.

Author: maeste

.github/workflows/run-tck.yml

@@ -29,7 +29,7 @@ jobs:
       - name: Checkout a2a-tck
         uses: actions/checkout@v4
         with:
-          repository: maeste/a2a-tck
+          repository: a2aproject/a2a-tck
           path: tck/a2a-tck
           ref: ${{ env.TCK_VERSION }}
       - name: Set up JDK 17