03-basics: Fix deprecation warnings and postgres version error (#12)

This change updates the s3 bucket resource syntax to use the newer
resource types for specifying versioning and encryption configs.
We also enable auto_minor_version_upgrade for the RDS instance and
switch to only asking for major version 12.

This will just use the default/latest RDS PostgreSQL v12 minor
version. Upside, the specific engine_version provided here will take
longer before it becomes invalid. Minor downside, we are saying its
OK for this RDS instance to undergo minor version upgrades, which
while fine for a toy example like this, is often not great in prod.

03-basics/aws-backend/main.tf

@@ -27,15 +27,20 @@ provider "aws" {
 resource "aws_s3_bucket" "terraform_state" {
   bucket        = "devops-directive-tf-state" # REPLACE WITH YOUR BUCKET NAME
   force_destroy = true
-  versioning {
-    enabled = true
-  }
+}
 
-  server_side_encryption_configuration {
-    rule {
-      apply_server_side_encryption_by_default {
-        sse_algorithm = "AES256"
-      }
+resource "aws_s3_bucket_versioning" "terraform_bucket_versioning" {
+  bucket = aws_s3_bucket.terraform_state.id
+  versioning_configuration {
+    status = "Enabled"
+  }
+}
+
+resource "aws_s3_bucket_server_side_encryption_configuration" "terraform_state_crypto_conf" {
+  bucket        = aws_s3_bucket.terraform_state.bucket 
+  rule {
+    apply_server_side_encryption_by_default {
+      sse_algorithm = "AES256"
     }
   }
 }