Bump @x-govuk/nhsuk-eleventy-plugin from 1.0.3 to 1.0.4 (#243)

Bumps [@x-govuk/nhsuk-eleventy-plugin](https://github.com/x-govuk/nhsuk-eleventy-plugin) from 1.0.3 to 1.0.4.
- [Release notes](https://github.com/x-govuk/nhsuk-eleventy-plugin/releases)
- [Commits](x-govuk/nhsuk-eleventy-plugin@v1.0.3...v1.0.4)

---
updated-dependencies:
- dependency-name: "@x-govuk/nhsuk-eleventy-plugin"
  dependency-version: 1.0.4
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]