message: fix(itk-js-cli): Correct default docker image tag
  This tag did not exist on DockerHub.
diff: @@ -38,7 +38,7 @@ const build = (sourceDir) => {
  process.exit(dockerVersion.status)
  }
  - let dockerImage = 'insighttoolkit/itk-js:20210517-7d190d5'
  + let dockerImage = 'insighttoolkit/itk-js:20210520-bafb1b5'
  if (program.commands[0].image) {
  dockerImage = program.commands[0].image
  }
  