Upgrade terraform AWS provider (#356)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

**Chores**
- Upgraded AWS provider to version 6.18.0 across production and quality
assurance environments.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: devksingh4

terraform/envs/prod/.terraform.lock.hcl

@@ -2,7 +2,7 @@ terraform {
   required_providers {
     aws = {
       source  = "hashicorp/aws"
-      version = "~> 6.17.0"
+      version = "~> 6.18.0"
     }
   }
 

terraform/envs/prod/main.tf

@@ -2,7 +2,7 @@ terraform {
   required_providers {
     aws = {
       source  = "hashicorp/aws"
-      version = "~> 6.17.0"
+      version = "~> 6.18.0"
     }
   }