feat: initial implementation (#1)

Terraform Plan Log

Terraform used the selected providers to generate the following execution
plan. Resource actions are indicated with the following symbols:
  + create

Terraform will perform the following actions:

  # github_actions_secret.test_secret will be created
  + resource "github_actions_secret" "test_secret" {
      + created_at      = (known after apply)
      + id              = (known after apply)
      + plaintext_value = (sensitive value)
      + repository      = "tf-test"
      + secret_name     = "SECRET_NAME"
      + updated_at      = (known after apply)
    }

Plan: 1 to add, 0 to change, 0 to destroy.

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Note: You didn't use the -out option to save this plan, so Terraform can't
guarantee to take exactly these actions if you run "terraform apply" now.