self conflicts with cidr_blocks error fix

[maximmi]

what

• default value for self field of security group rule changed to null

why

• With the provider hashicorp/aws v3.38.0 new restrictions have been added to aws_security_group_rule resource

references

• closes #13
• https://github.com/hashicorp/terraform-provider-aws/issues/15606
• https://github.com/hashicorp/terraform-provider-aws/pull/18467

[maximmi]

/test all

[maximmi]

/test all