Update for terraform 1.x.x and OCI provider 4.x.x

[kral2]

Terraform 0.12 is already EOL. There are some syntax that works in 0.12 but not in 1.0.0 anymore. Unless customers still plan on using 0.12, I think you should bump this to 1.0.0

Originally posted by @hyder in #68 (comment)

[vadyochik]

Looks like this was already done: https://github.com/oracle-terraform-modules/terraform-oci-compute-instance/blob/main/versions.tf

terraform {
  required_providers {
    oci = {
      source  = "oracle/oci"
      version = ">=4.67.3"
    }
  }
  required_version = ">= 1.0.0"
}