chore(deps): update terraform null to v3 (#275)

Author: renovate[bot]

test/setup/versions.tf

@@ -27,7 +27,7 @@ terraform {
     }
     null = {
       source  = "hashicorp/null"
-      version = "~> 2.1"
+      version = "~> 3.0"
     }
     random = {
       source  = "hashicorp/random"