title: How to convert string to uppercase in CloudFormation template
body: <p>I have the following piece in my CloudFormation template</p>
  
  <pre><code> PublicSubnetA:
      Type: AWS::EC2::Subnet
      Properties:
        VpcId: !Ref VPC
        CidrBlock: 10.1.10.0/24
        AvailabilityZone: !Select [ 0, !GetAZs ]    # Get the first AZ in the list        
        Tags:
        - Key: Name
          Value: !Sub
            - ${AWS::StackName}-PUB-${SUFFIX}
            - SUFFIX: !Select [ 0, !GetAZs ]
  </code></pre>
  
  <p>I need SUFFIX to be in uppercase, how do I do it?</p>