Update CI and doc

* Update to make sure that only one integration tests are run at one
  time
* Update refernce to build file.

.github/workflows/integration-tests.yaml

@@ -19,7 +19,7 @@ jobs:
     permissions:
       id-token: write
     concurrency:
-      group: ${{ github.workflow }}-${{ github.ref }}
+      group: integration-tests
       cancel-in-progress: false
     steps:
       - uses: actions/checkout@v4

README.md

@@ -1,6 +1,6 @@
 # Sceptre
 
-[![GitHub Actions Workflow Status](https://img.shields.io/github/actions/workflow/status/Sceptre/sceptre/main.yaml)](https://github.com/Sceptre/sceptre/actions/workflows/main.yaml)
+[![GitHub Actions Workflow Status](https://img.shields.io/github/actions/workflow/status/Sceptre/sceptre/gate.yaml)](https://github.com/Sceptre/sceptre/actions/workflows/gate.yaml)
 [![Docker Image Version (latest semver)](https://img.shields.io/docker/v/sceptreorg/sceptre?logo=docker&sort=semver)](https://hub.docker.com/r/sceptreorg/sceptre)
 [![PyPI](https://img.shields.io/pypi/v/sceptre?logo=pypi)](https://pypi.org/project/sceptre/)
 [![PyPI - Status](https://img.shields.io/pypi/status/sceptre?logo=pypi)](https://pypi.org/project/sceptre/)