fix: don't use rulesets for non-enterprise accounts

[bzarboni1]

ISSUE

[#43]

When running the bootstrap layer for a new organization, the terraform apply fails:

╷
│ Error: POST https://api.github.com/orgs/benz-playground/rulesets: 403 Upgrade to GitHub Enterprise to enable this feature. []
│ 
│   with module.github_foundations.module.base_ruleset.github_organization_ruleset.ruleset[0],
│   on .terraform/modules/github_foundations/modules/ruleset/organization_ruleset.tf line 1, in resource "github_organization_ruleset" "ruleset":
│    1: resource "github_organization_ruleset" "ruleset" {
│