ci(deps): Setup dependabot for Github Actions

[mydea]

While it makes sense for us to not run dependabot for general dependencies, we should be able to run it for Github Actions at least. This will create PRs once a month for any GHA that has a newer version available. (e.g. update @actions/checkout@v3 to @actions/checkout@v4 or similar stuff).

See: https://docs.github.com/en/code-security/dependabot/working-with-dependabot/keeping-your-actions-up-to-date-with-dependabot

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser - ES5 CDN Bundle (gzipped + minified)	19.51 KB (+0.06% 🔺)
@sentry/browser - ES5 CDN Bundle (minified)	60.36 KB (+0.05% 🔺)
@sentry/browser - ES6 CDN Bundle (gzipped + minified)	18.17 KB (+0.07% 🔺)
@sentry/browser - ES6 CDN Bundle (minified)	53.71 KB (+0.03% 🔺)
@sentry/browser - Webpack (gzipped + minified)	19.9 KB (+0.03% 🔺)
@sentry/browser - Webpack (minified)	65.12 KB (+0.04% 🔺)
@sentry/react - Webpack (gzipped + minified)	19.93 KB (+0.07% 🔺)
@sentry/nextjs Client - Webpack (gzipped + minified)	45.89 KB (+0.03% 🔺)
@sentry/browser + @sentry/tracing - ES5 CDN Bundle (gzipped + minified)	26.33 KB (+0.03% 🔺)
@sentry/browser + @sentry/tracing - ES6 CDN Bundle (gzipped + minified)	24.74 KB (+0.05% 🔺)

[Lms24]

Looks like a good change to me 👍