Set ipv6 properties even if no ipv6 is enabled in subnet

[pdecat]

This allows usage in conditionals.

Fixes #688 but for subnet instead of VPC

Changes proposed in this pull request:

• Set ipv6 properties even if no ipv6 is enabled in subnet

Output from acceptance testing:

# make testacc TESTARGS='-run=TestAccAWSSubnet_basic'
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./... -v -parallel 20 -run=TestAccAWSSubnet_basic -timeout 120m
?       github.com/terraform-providers/terraform-provider-aws   [no test files]
=== RUN   TestAccAWSSubnet_basic
=== PAUSE TestAccAWSSubnet_basic
=== CONT  TestAccAWSSubnet_basic
--- PASS: TestAccAWSSubnet_basic (53.21s)
PASS
ok      github.com/terraform-providers/terraform-provider-aws/aws       53.231s

[bflad]

Thanks so much for this fix, @pdecat! 🚀

--- PASS: TestAccAWSSubnet_basic (7.53s)
--- PASS: TestAccAWSSubnet_importBasic (10.29s)
--- PASS: TestAccAWSSubnet_enableIpv6 (13.95s)
--- PASS: TestAccAWSSubnet_ipv6 (19.63s)

[bflad]

This was released (4 days ago) in version 1.47.0 of the AWS provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. Thanks!