feat: add pre-commit check in ci

- add a ci workflow to verify pre-commit passes
- fix pre-commit errors/warnings:
  - missing required_version
  - missing required_providers
  - fixed terraform_deprecated_interpolation
  - removed terraform_unused_declarations

modules/vault_cluster/variables.tf

@@ -166,7 +166,6 @@ variable "pki_secret_backend" {
     crl_distribution_points       = optional(list(string), [])
     ocsp_servers                  = optional(list(string), [])
     enable_templating             = optional(bool, false)
-    default_issuer_ref            = optional(string)
     default_follows_latest_issuer = optional(bool, false)
     crl_expiry                    = optional(string, "72h")
     crl_disable                   = optional(bool, false)
@@ -204,7 +203,6 @@ variable "pki_mount_only" {
   type = map(object({
     description                   = optional(string)
     max_lease_ttl_seconds         = optional(number, 315360000)
-    issuer_ref                    = optional(string, "default")
     issuing_certificates          = optional(list(string), [])
     crl_distribution_points       = optional(list(string), [])
     ocsp_servers                  = optional(list(string), [])