message: Avoid error when using
  The following throws an error when using `@babel/parser@7.0.0-beta.52`:
  ```js
  let parser = require('recast/parsers/babylon');
  parser.parse('let foo = "whatever"');
  ```
  With the following error:
  ```
  'pipelineOperator' requires 'proposal' option whose value should be one of: minimal
  ```
  This change to `parsers/_babylon_options.js` avoids the error.
diff: @@ -32,7 +32,7 @@ module.exports = function (options) {
  "objectRestSpread",
  "optionalCatchBinding",
  "optionalChaining",
  - "pipelineOperator",
  + ["pipelineOperator", { proposal: "minimal" }],
  "throwExpressions",
  ]
  };
  