fix: (run-tck): update TCK repository reference (#175)

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.

# Description

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Fixes #<issue_number_goes_here> 🦕

Author: maeste

.github/workflows/run-tck.yml

@@ -11,7 +11,7 @@ on:
 
 env:
   # Tag of the TCK
-  TCK_VERSION: 0.2.3
+  TCK_VERSION: v0.2.3
   # Tells uv to not need a venv, and instead use system
   UV_SYSTEM_PYTHON: 1
 
@@ -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