Fix CI integration tests by migrating to docker compose v2

The standalone `docker-compose` (v1) binary is no longer installed on
GitHub Actions ubuntu-latest runners. Use the `docker compose` plugin
subcommand instead.

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

Author: nsa-softpay

.github/workflows/tests.yml

@@ -47,9 +47,9 @@ jobs:
       - name: Integration Test
         id: integration-test
         run: |
-          docker-compose -f docker-compose.ci.yaml build sut
-          docker-compose -f docker-compose.ci.yaml up --exit-code-from sut
-          docker-compose -f docker-compose.ci.yaml rm --stop --force
+          docker compose -f docker-compose.ci.yaml build sut
+          docker compose -f docker-compose.ci.yaml up --exit-code-from sut
+          docker compose -f docker-compose.ci.yaml rm --stop --force
       - uses: act10ns/slack@v2
         with:
           status: ${{ job.status }}