CI is the practice of automating the integration of code changes from multiple contributors into a single software project. There are a few tools that you can use for continuous integration.
Note that your project submission is going to be tested locally.
Please ensure that your project builds correctly on local machines, even if it builds successfully on CI tools.
Jenkins is one of the tools that you can use for kick-starting CI directly in your repository. It provides hundreds of plugins to support building, deploying and automating any project.
You can look into how to integrate your repository with Jenkins here and here.
GitHub Actions is another tool that you can use. It makes use of workflows, which are custom automated processes that you can set up in your repository to build, test, package, release or deploy any project on GitHub. A workflow should be configured using YAML syntax, and save them as workflow files in your repository. You must store workflows in the .github/workflows directory in the root of your repository.
Please refer GitHub Docs on GitHub Actions for more information.
The following are sample workflows that you can use for Github Actions.
Workflow for building on Windows CMake solution
Workflow for building on MacOS
Workflow for building on Linux
Notes: