Fix: single_nat_gateway with enable=false attribute

[h1manshu98]

what

• Updated single_nat_gateway creation condition when enable = false is used for below error -

│ Error: Error in function call
│
│ on ../../main.tf line 319, in resource "aws_nat_gateway" "private":
│ 319: subnet_id = length(aws_subnet.public) > 0 ? element(aws_subnet.public[*].id, count.index) : element(var.public_subnet_ids, count.index)
│ ├────────────────
│ │ while calling element(list, index)
│ │ count.index is 0
│
│ Call to function "element" failed: cannot use element function with an empty list.

[13archit]

LGTM

[omsharma07]

LGTM