Update destroy_branch.py

Update codebuild image to the latest (standard:6.0)

Author: iriskraja77

cdk_pipelines_multi_branch/cicd/code/destroy_branch.py

@@ -54,7 +54,7 @@ def handler(event, context):
                 },
                 environment={
                     'type': 'LINUX_CONTAINER',
-                    'image': 'aws/codebuild/standard:4.0',
+                    'image': 'aws/codebuild/standard:6.0',
                     'computeType': 'BUILD_GENERAL1_SMALL'
                 },
                 serviceRole=role_arn