fix(gatsby): pin webpack to fix unexpected token error during build (#11640)
fix(gatsby): pin webpack to fix unexpected token error during build (#11640)

## Description

This addresses #11198.

There's a regression bug webpack/webpack#8656 affecting 4.29.0 through at least 4.29.3 which causes errors like this during `gatsby build`.

  Error: ./.cache/async-requires.js 8:11
  Module parse failed: Unexpected token (8:11)
  You may need an appropriate loader to handle this file type.
  | exports.components = {
  |   "component---frontend-components-main-js": function componentFrontendCompo  nentsMainJs() {
  >     return import("/home/circleci/project/frontend/components/main.js"
  |     /* webpackChunkName: "component---frontend-components-main-js" */
  |     );
   @ ./.cache/production-app.js 18:0-45 21:23-36 26:23-36

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## Related Issues

- Addresses #11198
- Related to webpack/webpack#8656

ilcm96/ilcm96.github.io