Opt in to coverage by security advisory policy

Cleaned up the issue title and summary and added to the "Above and beyond tasks" in 🌱 Stripe Webhooks 2.0.0 stable release plan Active .

Without a stable release, opting the project into security advisory policy does not have any effect, as development snapshots and non stable releases are not covered by the security advisory policy.

@apaderno, that’s correct, which is why this is stipulated in the issue summary.

Once…a 2.0.0 release is published…