Function isEventKey

Returns key is
    | "pr:comment:added"
    | "pr:comment:deleted"
    | "pr:comment:edited"
    | "pr:declined"
    | "pr:deleted"
    | "pr:from_ref_updated"
    | "pr:merged"
    | "pr:modified"
    | "pr:opened"
    | "pr:reviewer:approved"
    | "pr:reviewer:changes_requested"
    | "pr:reviewer:unapproved"
    | "pr:reviewer:updated"
    | "project:modified"
    | "mirror:repo_synchronized"
    | "repo:comment:added"
    | "repo:comment:deleted"
    | "repo:comment:edited"
    | "repo:forked"
    | "repo:modified"
    | "repo:refs_changed"
    | "repo:secret_detected"