bug(cloudformation): Trivy sometimes fails to recognise string interpretations of Boolean values

[nikpivkin]

Successfully:

Resources:
  GoodExample:
    Type: AWS::EC2::Volume
    Properties: 
      Size: 100
      Encrypted: "true" # <---
      KmsKeyId: "alias/volumeEncrypt"
    DeletionPolicy: Snapshot

Didn't recognise it:

AWSTemplateFormatVersion: 2010-09-09
Resources:
  MyEC2Instance:
    Type: AWS::EC2::Instance
    Properties:
      ImageId: "ami-79fd7eee"
      KeyName: "testkey"
      BlockDeviceMappings:
      - DeviceName: "/dev/sdm"
        Ebs:
          VolumeType: "io1"
          Iops: "200"
          DeleteOnTermination: "false"
          VolumeSize: "20"
          Encrypted: "true" # <---

HIGH: Root block device is not encrypted.
════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════
Block devices should be encrypted to ensure sensitive data is held securely at rest.

See https://avd.aquasec.com/misconfig/avd-aws-0131
────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
 test.yaml:15
────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
  15 [           Encrypted: "true" # <---
────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────

Ref:

• https://www.awholenother.com/2020/06/20/boolean-parameters-in-cloudformation.html
• https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/template-formats.html