terraform: update terraform providers to new format

This commit updates the versions.tf and terraform providers to the
required format for 0.13 version.

Signed-off-by: Imran Pochi <imran@kinvolk.io>

assets/terraform-modules/kvm-libvirt/flatcar-linux/kubernetes/versions.tf

@@ -1,13 +1,23 @@
 # Terraform version and plugin versions
 
 terraform {
-  required_version = ">= 0.12.0"
+  required_version = ">= 0.13"
 
   required_providers {
-    ct       = "0.6.0"
+
+    ct = {
+      source  = "poseidon/ct"
+      version = "0.6.1"
+    }
+
+    libvirt = {
+      source = "dmacvicar/libvirt"
+      uri     = "qemu:///system"
+      version = "0.6.2"
+    }
+
     null     = "2.1.2"
     template = "2.1.2"
-    libvirt  = "0.6.0"
     random   = "2.3.0"
   }
 }

assets/terraform-modules/kvm-libvirt/flatcar-linux/kubernetes/workers/versions.tf

@@ -1,11 +1,19 @@
 # Terraform version and plugin versions
 
 terraform {
-  required_version = ">= 0.12.0"
+  required_version = ">= 0.13"
 
   required_providers {
-    ct       = "0.6.0"
+    ct = {
+      source  = "poseidon/ct"
+      version = "0.6.1"
+    }
+
+    libvirt = {
+      source = "dmacvicar/libvirt"
+      uri     = "qemu:///system"
+      version = "0.6.2"
+    }
     template = "2.1.2"
-    libvirt  = "0.6.0"
   }
 }

pkg/platform/kvmlibvirt/template.go

@@ -120,36 +120,23 @@ module "worker-pool-{{ $index }}" {
 }
 {{- end }}
 
-provider "libvirt" {
-  uri     = "qemu:///system"
-  version = "~> 0.6.0"
-}
-
-provider "ct" {
-  version = "~> 0.5.0"
-}
-
-provider "local" {
-  version = "~> 1.2"
-}
-
-provider "null" {
-  version = "~> 2.1"
+terraform {
+  required_providers {
+    libvirt = {
+			source = "dmacvicar/libvirt"
+			uri     = "qemu:///system"
+			version = "0.6.2"
+    }
+    ct = {
+			source  = "poseidon/ct"
+			version = "0.6.1"
+    }
+  }
 }
 
-provider "template" {
-  version = "~> 2.1"
-}
-
-provider "tls" {
-  version = "~> 2.0"
-}
-
-provider "random" {
-  version = "~> 2.2"
+provider "libvirt" {
+	uri     = "qemu:///system"
 }
-
-
 # Stub output, which indicates, that Terraform run at least once.
 # Used when checking, if we should ask user for confirmation, when
 # applying changes to the cluster.