feat(github-actions): support GitHub actions runners (#23633)

lib/modules/datasource/api.ts

lib/modules/datasource/github-runners/index.spec.ts

lib/modules/datasource/github-runners/index.ts

lib/modules/datasource/github-runners/readme.md

...manager/github-actions/__snapshots__/extract.spec.ts.snap

lib/modules/manager/github-actions/extract.spec.ts

lib/modules/manager/github-actions/extract.ts

lib/modules/manager/github-actions/index.ts

lib/modules/manager/github-actions/readme.md

lib/modules/manager/github-actions/types.ts