chore(terraform): auto-applied ".github/SECURITY.md" [skip ci]

this file was auto-applied from the "github-common-files" module
located here:
  - https://github.com/lrstanley/.github/tree/master/terraform/github-common-files

instructions on how to tell Terraform to exclude this file:
  - https://github.com/lrstanley/.github/blob/master/example.ci-config.yml

Signed-off-by: Liam Stanley <me@liamstanley.io>