Add Dependabot #1159
Description
We should be used dependabot to keep the GitHub actions up to date. I released vcpkg-action@v7 which fixes issues with caching. An update pull request will be automatically generated if dependabot is configured. See https://docs.github.com/en/code-security/dependabot/working-with-dependabot/keeping-your-actions-up-to-date-with-dependabot