ci(release-please): don't use manifest (#67)

* ci(release-please): configure manifest for root

* ci(release-please): tmp run `on-main` workflow on branch `ci/release-please/configure-manifest`

* ci(release-please): configure manifest with empty project

* ci(release-please): don't use manifest

Author: alex-mcgovern

.github/workflows/_release-please.yml

@@ -16,4 +16,3 @@ jobs:
         with:
           token: ${{ secrets.GH_PAT_RELEASE_PLEASE }}
           config-file: release-please-config.json
-          manifest-file: release-please-manifest.json