provider/aws: aws_ses_receipt_rule: fix off-by-one errors (#12961)
provider/aws: aws_ses_receipt_rule: fix off-by-one errors (#12961)

In function `resourceAwsSesReceiptRuleRead` the position of the receipt
rules in the rule set was taken directly from the index of the rule's
position in the slice returned by the AWS API call. As the slice is
zero-based and the ruleset is one-based, this results in an incorrect
representation.

This manifests as `aws_ses_receipt_rule` resources always showing a
diff during plan or apply.
kjmkznr/terraform-provider-aws,kjmkznr/terraform-provider-aws,charles-at-geospock/terraform-provider-aws,nbaztec/terraform-provider-aws,nbaztec/terraform-provider-aws,Ninir/terraform-provider-aws,ashinohara/terraform-provider-aws,ClementCunin/terraform-provider-aws,ashinohara/terraform-provider-aws,ClementCunin/terraform-provider-aws,charles-at-geospock/terraform-provider-aws,ashinohara/terraform-provider-aws,charles-at-geospock/terraform-provider-aws,Ninir/terraform-provider-aws,terraform-providers/terraform-provider-aws,charles-at-geospock/terraform-provider-aws,kjmkznr/terraform-provider-aws,ClementCunin/terraform-provider-aws,Ninir/terraform-provider-aws,terraform-providers/terraform-provider-aws,Ninir/terraform-provider-aws,ClementCunin/terraform-provider-aws,terraform-providers/terraform-provider-aws,nbaztec/terraform-provider-aws,kjmkznr/terraform-provider-aws,terraform-providers/terraform-provider-aws,nbaztec/terraform-provider-aws,ashinohara/terraform-provider-aws