Update deprecated field name

mvanlonden · Rayraegah · commit c300b31ddf44 · 2022-10-21T21:16:05.000+09:00
```
╷
│ Warning: Argument is deprecated
│
│   with module.hasura.aws_db_instance.hasura,
│   on .terraform/modules/hasura/main.tf line 180, in resource "aws_db_instance" "hasura":
│  180:   name                   = var.rds_db_name
│
│ Use db_name instead
│
│ (and 2 more similar warnings elsewhere)
```
diff --git a/main.tf b/main.tf
@@ -177,7 +177,7 @@ resource "aws_db_subnet_group" "hasura" {
 }
 
 resource "aws_db_instance" "hasura" {
-  name                   = var.rds_db_name
+  db_name                = var.rds_db_name
   identifier             = "hasura"
   username               = var.rds_username
   password               = var.rds_password

Original file line number	Diff line number	Diff line change
`@@ -177,7 +177,7 @@ resource "aws_db_subnet_group" "hasura" {`
`177`	`177`	`}`
`178`	`178`
`179`	`179`	`resource "aws_db_instance" "hasura" {`
`180`		`- name = var.rds_db_name`
	`180`	`+ db_name = var.rds_db_name`
`181`	`181`	`identifier = "hasura"`
`182`	`182`	`username = var.rds_username`
`183`	`183`	`password = var.rds_password`