Update Terraform terraform-aws-modules/notify-slack/aws to 4.18

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
terraform-aws-modules/notify-slack/aws (source)	module	minor	4.12 -> 4.18

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Release Notes

terraform-aws-modules/terraform-aws-notify-slack

v4.18.0

Compare Source

• feat: Added support for GuardDuty Findings format (#​143)

v4.17.0

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• feat: Allow custom attachement (#​123)

v4.16.0

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• feat: add support for nested messages (#​142)

v4.15.0

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• chore: Remove check boxes that don't render properly in module doc (#​140)
• chore: update CI/CD to use stable terraform-docs release artifact and discoverable Apache2.0 license (#​138)

v4.14.0

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• feat: Updated code to support Terraform 0.15 (#​136)
• chore: update documentation and pin terraform_docs version to avoid future changes (#​134)

v4.13.0

Compare Source

• fix: use the current aws partition (#​133)
• chore: align ci-cd static checks to use individual minimum Terraform versions (#​131)
• fix: Remove data resource for sns topic to avoid race condition (#​81)
• chore: add ci-cd workflow for pre-commit checks (#​128)
• feat: Improve slack message formatting for generic messages (#​124)
• chore: update documentation based on latest terraform-docs which includes module and resource sections (#​126)
• feat: add support for GovCloud URLs (#​114)
• feat: Allow Lambda function to be VPC bound (#​122)
• feat: Updated version of terraform-aws-lambda module to 1.28.0 (#​119)
• feat: Updated version of Terraform AWS Lambda module to support multiple copies (#​117)
• fix: Typo on subscription_filter_policy variable (#​113)
• docs: Added a note about using with Terraform Cloud Agents (#​108)
• feat: allow reuse of existing lambda_role (#​85)
• fix: Fix regression with aws_cloudwatch_log_group resource after upgrade of AWS provider 3.0 (#​106)
• docs: Updated version of module to use for Terraform 0.12 users
• fix: Updated version requirements to be Terraform 0.13 only (#​101)
• feat: Updated Lambda module to work with Terraform 0.13 (#​99)
• fix: Bump version of lambda module that supports Terraform 13 and AWS Provider 3.x (#​96)

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[cloudposse-mergebot]

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[mergify]

This pull request is now in conflict. Could you fix it @renovate[bot]? 🙏