Update the script for google provider 2.0.0

[anonyknight]

Using the latest google provider 3.54.0 will have the following errors:

Error: Unsupported argument

on .terraform/modules/vault_cluster/modules/vault-cluster/main.tf line 60, in resource "google_compute_region_instance_group_manager" "vault":
60: instance_template = data.template_file.compute_instance_template_self_link.rendered

An argument named "instance_template" is not expected here.

Error: Unsupported argument

on .terraform/modules/vault_cluster/modules/vault-cluster/main.tf line 66, in resource "google_compute_region_instance_group_manager" "vault":
66: update_strategy = var.instance_group_update_strategy

An argument named "update_strategy" is not expected here.

update_strategy was documented in
https://registry.terraform.io/providers/hashicorp/google/latest/docs/guides/version_2_upgrade

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[robmorgan]

@anonyknight thanks for your contribution! This PR includes some of the same functionality we are hoping to introduce in #55, however the problem we are facing is that for some reason Vault is unable to discover other nodes in the cluster likely due to a Consul DNS issue. As #55 includes a lot more additional functionality I'll close this PR, however feel free to test #55, see if it works for you and optionally submit any necessary fixes. Thanks!